/* ============================================================
   CẨM NANG ĐẠO HIẾU ĐẠI VIỆT PHẢ — STYLE.CSS
   Design Style: Editorial · Sách Di Sản · Ấm Áp · Sang Trọng
   Pure Vanilla CSS3
   ============================================================ */

/* ------------------------------------------------------------
   1. CSS VARIABLES & DESIGN TOKENS
   ------------------------------------------------------------ */
:root {
    /* Brand Palette — Inspired by Trang Bìa (Daylight Azure Sky, Golden Tree, Amber Ribbon, Soft Cloud Mist) */
    --red: #168FE8;
    /* Primary Action: Vibrant Sky Azure */
    --red-hover: #086FBE;
    /* Deep Royal Blue Hover */
    --red-subtle: rgba(22, 143, 232, 0.08);
    --red-border: rgba(22, 143, 232, 0.25);

    --primary-blue: #168FE8;
    --primary-dark: #09599E;
    --primary-light: #E1F2FE;
    --azure: #0B7BD6;
    --cyan: #38BDF8;
    --cyan-glow: rgba(56, 189, 248, 0.35);
    --coral: #FF7043;
    --coral-hover: #E65100;

    --gold: #F59E0B;
    /* Radiant Sunlight Gold */
    --gold-light: #FCD34D;
    /* Golden Leaf Highlights */
    --gold-dark: #D97706;
    /* Amber Wood Gold */
    --gold-subtle: rgba(245, 158, 11, 0.12);
    --gold-border: rgba(245, 158, 11, 0.28);

    --cream: #EBF4FC;
    /* Fresh Sky Tint Cream */
    --cream-light: #F5F9FD;
    /* Luminous Gentle Daylight */
    --cream-dark: #DCECF9;
    /* Deep Ice Blue Accent */

    --ivory: #FFFFFF;
    /* Crisp White for Card Surfaces */
    --ivory-translucent: rgba(245, 250, 255, 0.94);
    --body-bg: #F2F7FC;
    /* Fresh Sky Ambient Page Background (Không bị sáng trắng quá) */
    --paper-bg: #EDF5FC;
    /* Fresh Luminous Background */
    --paper-texture: #E3EFF9;

    --brown: #163B66;
    /* Deep Navy Slate */
    --brown-light: #2563EB;
    /* Vibrant Royal Accent */
    --brown-dark: #0A2240;
    /* Midnight Slate - High Contrast Deep Heading */

    --text: #142F50;
    /* Rich Navy-Slate Body Text (Rõ ràng, dịu mắt, không chói lóa) */
    --text-muted: #3E5777;
    /* Slate Mid-Tone Subtext */
    --text-light: #5E7796;
    /* Soft Slate Metadata */
    --white: #FFFFFF;

    /* Typography */
    --font-heading: 'Playfair Display', Georgia, serif;
    --font-body: 'Be Vietnam Pro', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-serif-accent: 'Lora', Georgia, serif;

    /* Spacing & Layout */
    --container-max: 1320px;
    --container-pad: 32px;
    --section-pad-y: 110px;
    --section-pad-y-sm: 70px;

    /* Shadows & Borders */
    --shadow-soft: 0 10px 30px rgba(10, 34, 64, 0.05);
    --shadow-card: 0 16px 40px rgba(10, 34, 64, 0.07);
    --shadow-book: 0 25px 60px -15px rgba(10, 34, 64, 0.14), 0 0 0 1px rgba(56, 189, 248, 0.25);
    --shadow-gold: 0 8px 24px rgba(245, 158, 11, 0.22);
    --shadow-blue: 0 8px 24px rgba(22, 143, 232, 0.28);

    --radius-sm: 8px;
    --radius-md: 14px;
    --radius-lg: 22px;
    --radius-pill: 9999px;

    /* Transitions */
    --transition-smooth: all 0.35s cubic-bezier(0.22, 1, 0.36, 1);
    --transition-snappy: all 0.2s ease-out;
}

/* ------------------------------------------------------------
   2. CSS RESET & GLOBAL BASE
   ------------------------------------------------------------ */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-body);
    background-color: var(--body-bg);
    color: var(--text);
    line-height: 1.75;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    position: relative;
    background-image: radial-gradient(rgba(22, 143, 232, 0.05) 1px, transparent 1px);
    background-size: 32px 32px;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: inherit;
    text-decoration: none;
    transition: var(--transition-snappy);
}

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
    transition: var(--transition-smooth);
}

input,
select,
textarea {
    font-family: inherit;
    font-size: 1rem;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--ivory);
}

::-webkit-scrollbar-thumb {
    background: var(--gold-light);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--gold);
}

/* Accessibility Focus */
:focus-visible {
    outline: 2px solid var(--red);
    outline-offset: 3px;
}

/* ------------------------------------------------------------
   3. TYPOGRAPHY & COMMON REUSABLE STYLES
   ------------------------------------------------------------ */
h1,
h2,
h3,
h4,
h5,
h6 {
    font-family: var(--font-heading);
    color: var(--brown-dark);
    font-weight: 600;
    line-height: 1.3;
    letter-spacing: -0.01em;
    overflow-wrap: break-word;
    word-break: break-word;
}

p,
span,
a,
li,
td,
th,
button {
    overflow-wrap: break-word;
}

.container {
    width: 100%;
    max-width: var(--container-max);
    margin-left: auto;
    margin-right: auto;
    padding-left: var(--container-pad);
    padding-right: var(--container-pad);
    box-sizing: border-box;
}

.chapter-section {
    padding-top: var(--section-pad-y);
    padding-bottom: var(--section-pad-y);
    position: relative;
    width: 100%;
    overflow-x: hidden;
}

.chapter-label {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-family: var(--font-body);
    font-size: 0.8125rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.18em;
    color: var(--gold-dark);
    margin-bottom: 16px;
    position: relative;
}

.chapter-label::before {
    content: "";
    display: inline-block;
    width: 24px;
    height: 1px;
    background-color: var(--gold);
}

.section-headline {
    font-size: clamp(2rem, 3.5vw, 2.75rem);
    font-weight: 700;
    color: var(--brown-dark);
    margin-bottom: 20px;
    line-height: 1.25;
}

.section-headline .highlight-red {
    color: var(--red);
    position: relative;
    display: inline-block;
}

.section-headline .highlight-gold {
    color: var(--gold-dark);
}

.section-desc {
    font-size: 1.125rem;
    color: var(--text-muted);
    max-width: 680px;
    line-height: 1.8;
}

.section-header-center {
    text-align: center;
    max-width: 780px;
    margin: 0 auto 56px auto;
}

.section-header-center .chapter-label::before {
    display: none;
}

.section-header-center .chapter-label {
    justify-content: center;
}

.divider-ornament {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    margin: 20px auto;
    color: var(--gold);
    opacity: 0.8;
}

.divider-ornament::before,
.divider-ornament::after {
    content: "";
    width: 48px;
    height: 1px;
    background: linear-gradient(to right, transparent, var(--gold-border), transparent);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 14px 28px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.9375rem;
    letter-spacing: 0.02em;
    cursor: pointer;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.btn-primary {
    background: linear-gradient(135deg, var(--red) 0%, var(--red-hover) 100%);
    color: #FFFFFF;
    border: 1px solid var(--red);
    box-shadow: 0 6px 18px rgba(22, 143, 232, 0.28);
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--red-hover) 0%, #033D8A 100%);
    border-color: var(--red-hover);
    transform: translateY(-2px);
    box-shadow: 0 10px 24px rgba(22, 143, 232, 0.38);
    color: var(--white);
}

.btn-outline {
    background: transparent;
    color: var(--brown-dark);
    border: 1px solid var(--red-border);
}

.btn-outline:hover {
    background-color: var(--cream);
    border-color: var(--red);
    color: var(--red);
    transform: translateY(-2px);
}

.btn-gold {
    background: linear-gradient(135deg, var(--gold-light) 0%, var(--gold) 100%);
    color: #0F223D;
    border: 1px solid var(--gold);
    box-shadow: 0 6px 18px rgba(245, 158, 11, 0.25);
    font-weight: 700;
}

.btn-gold:hover {
    background: linear-gradient(135deg, #FDE68A 0%, var(--gold-light) 100%);
    transform: translateY(-2px);
    color: #0F223D;
    box-shadow: 0 8px 24px rgba(245, 158, 11, 0.35);
}

.btn-icon {
    display: inline-flex;
    align-items: center;
    transition: transform 0.25s ease;
}

.btn:hover .btn-icon {
    transform: translateX(4px);
}

/* ------------------------------------------------------------
   4. HEADER
   ------------------------------------------------------------ */
.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 14px 0;
    background: var(--ivory-translucent);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid rgba(22, 143, 232, 0.12);
    box-shadow: 0 4px 20px rgba(15, 34, 61, 0.04);
    transition: padding 0.3s ease, box-shadow 0.3s ease;
}

.site-header.scrolled {
    padding: 12px 0;
    box-shadow: 0 6px 24px rgba(15, 34, 61, 0.08);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.brand-logo {
    display: flex;
    align-items: center;
    gap: 14px;
    color: var(--brown-dark);
}

.logo-symbol {
    width: 58px;
    height: 58px;
    border-radius: 0;
    object-fit: contain;
    border: none;
    background: transparent;
    padding: 0;
    box-shadow: none;
    transition: transform 0.3s ease;
    flex-shrink: 0;
}

.brand-logo:hover .logo-symbol {
    transform: scale(1.05);
    box-shadow: none;
}

.logo-text-group {
    display: flex;
    flex-direction: column;
}

.logo-main-title {
    font-family: 'Charm', 'Dancing Script', cursive, var(--font-heading);
    font-size: 1.85rem;
    font-weight: 400;
    color: #B86220; /* Màu nâu vàng hổ phách tươi sáng, thanh thoát */
    line-height: 1.05;
    letter-spacing: 0.02em;
    text-shadow: 0.5px 0.5px 1px rgba(120, 50, 10, 0.25);
    transition: transform 0.25s ease;
}

.logo-sub-title {
    font-family: var(--font-body);
    font-size: 0.6875rem;
    letter-spacing: 0.14em;
    color: var(--primary-blue); /* Màu xanh giống với tông màu chủ đạo của page */
    font-weight: 700;
    text-transform: uppercase;
    margin-top: 1px;
}

.desktop-nav {
    display: flex;
    align-items: center;
    gap: 32px;
}

.nav-item {
    font-size: 0.9375rem;
    font-weight: 500;
    color: #4A4036;
    position: relative;
    padding: 6px 0;
    transition: color 0.25s ease;
}

.nav-item::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 0%;
    height: 2px;
    background-color: var(--red);
    transition: width 0.3s ease;
}

.nav-item:hover,
.nav-item.active {
    color: var(--red);
}

.nav-item:hover::after,
.nav-item.active::after {
    width: 100%;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 16px;
}

#header-cta-btn {
    border-radius: var(--radius-pill);
    padding: 10px 24px;
    font-size: 0.9375rem;
    font-weight: 600;
    background-color: var(--red);
    border: 1px solid var(--red);
    color: #FFFFFF;
    box-shadow: 0 4px 14px rgba(152, 43, 43, 0.22);
}

#header-cta-btn:hover {
    background-color: var(--red-hover);
    border-color: var(--red-hover);
    transform: translateY(-2px);
    box-shadow: 0 8px 18px rgba(152, 43, 43, 0.32);
}

.hamburger-btn {
    display: none;
    width: 40px;
    height: 40px;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 5px;
    border-radius: var(--radius-sm);
    border: 1px solid var(--gold-border);
    background: var(--paper-bg);
    color: var(--brown-dark);
}

.hamburger-btn span {
    display: block;
    width: 20px;
    height: 2px;
    background-color: var(--brown-dark);
    transition: transform 0.3s ease, opacity 0.3s ease;
}

.hamburger-btn.open span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.hamburger-btn.open span:nth-child(2) {
    opacity: 0;
}

.hamburger-btn.open span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* Mobile Drawer */
.mobile-drawer {
    position: fixed;
    top: 0;
    right: 0;
    transform: translateX(100%);
    width: min(340px, 85vw);
    height: 100vh;
    background-color: var(--ivory);
    border-left: 1px solid var(--gold-border);
    box-shadow: -10px 0 30px rgba(0, 0, 0, 0.1);
    z-index: 1050;
    padding: 80px 30px 40px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    transition: transform 0.35s cubic-bezier(0.16, 1, 0.3, 1), visibility 0.35s ease;
    visibility: hidden;
}

.mobile-drawer.open {
    transform: translateX(0);
    visibility: visible;
}

.mobile-drawer-overlay {
    position: fixed;
    inset: 0;
    background: rgba(47, 30, 25, 0.4);
    backdrop-filter: blur(4px);
    z-index: 1040;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
}

.mobile-drawer-overlay.open {
    opacity: 1;
    visibility: visible;
}

.mobile-nav-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.mobile-nav-link {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    color: var(--brown-dark);
    display: block;
    padding: 8px 0;
    border-bottom: 1px dashed rgba(201, 154, 61, 0.25);
}

.mobile-nav-link:hover {
    color: var(--red);
    padding-left: 6px;
}



/* ------------------------------------------------------------
   7. HERO SECTION — TRANG BÌA (TRANG BÌA BANNER CINEMATIC & SPECIAL EFFECTS)
   ------------------------------------------------------------ */
.hero-section {
    margin-top: 86px;
    min-height: calc(100vh - 86px);
    display: flex;
    align-items: center;
    padding-top: 60px;
    padding-bottom: 90px;
    position: relative;
    background-color: #0B5FA5;
    background-image:
        radial-gradient(circle at var(--hero-mouse-x, 70%) var(--hero-mouse-y, 40%), rgba(56, 189, 248, 0.22) 0%, transparent 60%),
        linear-gradient(to right, rgba(8, 48, 88, 0.95) 0%, rgba(10, 68, 122, 0.88) 40%, rgba(14, 107, 184, 0.35) 70%, transparent 100%),
        url('../assets/images/trang_bia.png');
    background-position: right center;
    background-size: cover;
    background-repeat: no-repeat;
    overflow: hidden;
    border-bottom: 1px solid rgba(56, 189, 248, 0.25);
    perspective: 1200px;
}

/* Hero Ambient Aura Glow */
.hero-ambient-glow {
    position: absolute;
    top: -20%;
    left: 20%;
    width: 650px;
    height: 650px;
    background: radial-gradient(circle, rgba(56, 189, 248, 0.25) 0%, rgba(245, 158, 11, 0.12) 40%, transparent 70%);
    filter: blur(60px);
    pointer-events: none;
    z-index: 1;
    animation: auraFloat 10s ease-in-out infinite alternate;
}

@keyframes auraFloat {
    0% {
        transform: translate(-30px, -20px) scale(0.9);
        opacity: 0.7;
    }
    100% {
        transform: translate(40px, 30px) scale(1.15);
        opacity: 1;
    }
}

/* Canvas Particles */
.hero-particles-canvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 1;
}

/* Floating Heritage Decorations */
.hero-floating-decorations {
    position: absolute;
    inset: 0;
    pointer-events: none;
    z-index: 1;
    overflow: hidden;
}

.floating-star {
    position: absolute;
    color: #FCD34D;
    font-size: 1.25rem;
    filter: drop-shadow(0 0 8px rgba(245, 158, 11, 0.8));
    opacity: 0.75;
}

.star-1 {
    top: 22%;
    left: 48%;
    animation: floatStar1 7s ease-in-out infinite;
}

.star-2 {
    top: 65%;
    left: 42%;
    font-size: 0.95rem;
    color: #38BDF8;
    filter: drop-shadow(0 0 8px rgba(56, 189, 248, 0.8));
    animation: floatStar2 9s ease-in-out infinite 1s;
}

.star-3 {
    top: 35%;
    right: 18%;
    font-size: 1.4rem;
    animation: floatStar1 8s ease-in-out infinite 2s;
}

.floating-ring {
    position: absolute;
    width: 140px;
    height: 140px;
    border-radius: 50%;
    border: 1px dashed rgba(56, 189, 248, 0.3);
    top: 15%;
    right: 8%;
    animation: rotateRing 24s linear infinite;
}

@keyframes floatStar1 {
    0%, 100% {
        transform: translateY(0) scale(1) rotate(0deg);
        opacity: 0.6;
    }
    50% {
        transform: translateY(-22px) scale(1.2) rotate(45deg);
        opacity: 1;
    }
}

@keyframes floatStar2 {
    0%, 100% {
        transform: translateY(0) translateX(0) scale(1);
        opacity: 0.5;
    }
    50% {
        transform: translateY(-16px) translateX(12px) scale(1.15);
        opacity: 0.95;
    }
}

@keyframes rotateRing {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

.hero-container {
    position: relative;
    z-index: 2;
}

.hero-content {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    max-width: 650px;
    position: relative;
    z-index: 2;
    transform-style: preserve-3d;
    transition: transform 0.25s cubic-bezier(0.2, 0, 0.2, 1);
}

.hero-eyebrow-wrap {
    margin-bottom: 22px;
}

.hero-eyebrow {
    font-size: 0.8125rem;
    font-weight: 700;
    letter-spacing: 0.18em;
    color: var(--cyan);
    text-transform: uppercase;
    margin-bottom: 0;
    display: inline-flex;
    align-items: center;
    gap: 10px;
    background: rgba(56, 189, 248, 0.14);
    border: 1px solid rgba(56, 189, 248, 0.35);
    padding: 7px 18px;
    border-radius: var(--radius-pill);
    backdrop-filter: blur(12px);
    box-shadow: 0 4px 16px rgba(10, 34, 64, 0.2);
}

.hero-pulse-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: #38BDF8;
    box-shadow: 0 0 10px #38BDF8;
    display: inline-block;
    animation: pulseDot 2s ease-in-out infinite;
}

@keyframes pulseDot {
    0%, 100% {
        transform: scale(1);
        opacity: 1;
        box-shadow: 0 0 0 0 rgba(56, 189, 248, 0.7);
    }
    50% {
        transform: scale(1.25);
        opacity: 0.8;
        box-shadow: 0 0 0 7px rgba(56, 189, 248, 0);
    }
}

.hero-headline {
    font-size: clamp(2.6rem, 4.4vw, 3.85rem);
    font-weight: 700;
    line-height: 1.15;
    color: #FFFFFF;
    margin-bottom: 24px;
    letter-spacing: -0.01em;
    text-shadow: 0 4px 24px rgba(0, 0, 0, 0.45);
}

.hero-headline .headline-accent {
    color: var(--gold-light);
    background: linear-gradient(90deg, #FCD34D 0%, #FFFBEB 25%, #F59E0B 50%, #FFFBEB 75%, #FCD34D 100%);
    background-size: 200% auto;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    display: inline-block;
    animation: goldLightSweep 7s linear infinite;
    text-shadow: none;
}

@keyframes goldLightSweep {
    0% {
        background-position: 0% center;
    }
    100% {
        background-position: 200% center;
    }
}

.hero-desc {
    font-size: 1.125rem;
    color: rgba(255, 255, 255, 0.92);
    margin-bottom: 22px;
    line-height: 1.7;
    max-width: 540px;
    text-shadow: 0 2px 8px rgba(0, 0, 0, 0.35);
}

.hero-highlight {
    font-family: var(--font-body);
    font-style: normal;
    font-weight: 600;
    font-size: 1.0625rem;
    color: #FDE68A;
    margin-bottom: 34px;
    border-left: 3px solid var(--cyan);
    padding: 9px 18px;
    background: rgba(56, 189, 248, 0.12);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    line-height: 1.5;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.12);
    backdrop-filter: blur(8px);
}

.highlight-sparkle {
    display: inline-block;
    animation: sparkleSpin 4s ease-in-out infinite;
}

@keyframes sparkleSpin {
    0%, 100% {
        transform: scale(1) rotate(0deg);
    }
    50% {
        transform: scale(1.25) rotate(180deg);
    }
}

.hero-cta-group {
    display: flex;
    align-items: center;
    gap: 16px;
    flex-wrap: wrap;
}

.btn-hero-play {
    background: linear-gradient(135deg, #168FE8 0%, #0757B8 100%);
    color: #FFFFFF;
    border: 1px solid rgba(56, 189, 248, 0.6);
    border-radius: var(--radius-pill);
    padding: 14px 28px;
    font-weight: 700;
    font-size: 0.9375rem;
    box-shadow: 0 8px 24px rgba(22, 143, 232, 0.35), 0 0 16px rgba(56, 189, 248, 0.2);
    display: inline-flex;
    align-items: center;
    gap: 10px;
    transition: var(--transition-smooth);
}

.btn-hero-play:hover {
    background: linear-gradient(135deg, #0757B8 0%, #033D8A 100%);
    border-color: var(--cyan);
    color: #FFFFFF;
    transform: translateY(-3px) scale(1.02);
    box-shadow: 0 14px 32px rgba(22, 143, 232, 0.5), 0 0 20px rgba(56, 189, 248, 0.4);
}

.btn-hero-book {
    background-color: rgba(255, 255, 255, 0.14);
    color: #FFFFFF;
    border: 1px solid rgba(255, 255, 255, 0.4);
    border-radius: var(--radius-pill);
    padding: 14px 28px;
    font-weight: 600;
    font-size: 0.9375rem;
    backdrop-filter: blur(12px);
    box-shadow: 0 6px 18px rgba(0, 0, 0, 0.22);
    display: inline-flex;
    align-items: center;
    gap: 10px;
    transition: var(--transition-smooth);
}

.btn-hero-book:hover {
    background-color: rgba(255, 255, 255, 0.24);
    border-color: #FFFFFF;
    color: #FFFFFF;
    transform: translateY(-3px) scale(1.02);
    box-shadow: 0 10px 25px rgba(255, 255, 255, 0.15);
}

/* Scroll Indicator */
.hero-scroll-indicator {
    position: absolute;
    bottom: 24px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    color: rgba(255, 255, 255, 0.75);
    text-decoration: none;
    z-index: 3;
    transition: var(--transition-fast);
}

.hero-scroll-indicator:hover {
    color: #38BDF8;
    transform: translateX(-50%) translateY(-2px);
}

.scroll-mouse {
    width: 22px;
    height: 34px;
    border: 2px solid currentColor;
    border-radius: 12px;
    display: flex;
    justify-content: center;
    padding-top: 6px;
    box-sizing: border-box;
}

.scroll-wheel {
    width: 4px;
    height: 7px;
    background: currentColor;
    border-radius: 2px;
    animation: scrollWheelAnim 1.8s ease-in-out infinite;
}

@keyframes scrollWheelAnim {
    0% {
        transform: translateY(0);
        opacity: 1;
    }
    100% {
        transform: translateY(12px);
        opacity: 0;
    }
}

.scroll-text {
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

.btn-icon-svg {
    flex-shrink: 0;
}

/* ------------------------------------------------------------
   8. CHƯƠNG 1 — BỨC THƯ GỬI CON (VIDEO 16:9)
   ------------------------------------------------------------ */
.chapter-video-section {
    background-color: var(--paper-bg);
    background-image:
        linear-gradient(180deg, rgba(248, 252, 255, 0.94) 0%, rgba(234, 247, 255, 0.90) 50%, rgba(248, 252, 255, 0.96) 100%),
        url('../assets/images/family-memory-grandparents.png');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    border-top: 1px solid rgba(56, 189, 248, 0.2);
    border-bottom: 1px solid rgba(56, 189, 248, 0.2);
    position: relative;
}

.video-container {
    max-width: 960px;
    margin: 0 auto;
}

.video-wrapper {
    position: relative;
    width: 100%;
    aspect-ratio: 16 / 9;
    background-color: var(--brown-dark);
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-book);
    border: 4px solid var(--ivory);
    margin-bottom: 40px;
}

.video-element,
.youtube-video-frame {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
    border: none;
}

/* YouTube Showcase Facade Link */
.youtube-facade-link {
    position: relative;
    width: 100%;
    height: 100%;
    display: block;
    text-decoration: none;
    overflow: hidden;
}

.facade-thumb-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
    transition: transform 0.6s cubic-bezier(0.2, 0.8, 0.2, 1);
}

.youtube-facade-link:hover .facade-thumb-img {
    transform: scale(1.06);
}

.facade-overlay {
    position: absolute;
    inset: 0;
    background: linear-gradient(180deg, rgba(10, 34, 64, 0.35) 0%, rgba(10, 34, 64, 0.65) 60%, rgba(10, 34, 64, 0.92) 100%);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-between;
    padding: 24px;
    transition: background 0.3s ease;
}

.youtube-facade-link:hover .facade-overlay {
    background: linear-gradient(180deg, rgba(10, 34, 64, 0.2) 0%, rgba(10, 34, 64, 0.5) 50%, rgba(10, 34, 64, 0.85) 100%);
}

.facade-top-bar {
    width: 100%;
    display: flex;
    justify-content: flex-start;
}

.facade-badge {
    background: rgba(220, 38, 38, 0.9);
    color: #FFFFFF;
    font-size: 0.78rem;
    font-weight: 800;
    letter-spacing: 0.06em;
    padding: 6px 14px;
    border-radius: var(--radius-pill);
    text-transform: uppercase;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

.facade-center-action {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 14px;
}

.facade-play-btn {
    width: 84px;
    height: 84px;
    border-radius: 50%;
    background: linear-gradient(135deg, #EF4444 0%, #B91C1C 100%);
    color: #FFFFFF;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    box-shadow: 0 0 0 14px rgba(239, 68, 68, 0.3), 0 12px 30px rgba(0, 0, 0, 0.45);
    transition: transform 0.35s cubic-bezier(0.34, 1.56, 0.64, 1), box-shadow 0.35s ease;
    border: 3px solid rgba(255, 255, 255, 0.4);
}

.youtube-facade-link:hover .facade-play-btn {
    transform: scale(1.14);
    box-shadow: 0 0 0 20px rgba(239, 68, 68, 0.45), 0 16px 40px rgba(0, 0, 0, 0.6);
}

.facade-play-label {
    font-family: var(--font-heading);
    font-size: 1.15rem;
    font-weight: 700;
    color: #FFFFFF;
    letter-spacing: 0.05em;
    text-shadow: 0 2px 8px rgba(0, 0, 0, 0.7);
}

.facade-bottom-info {
    text-align: center;
    max-width: 600px;
}

.facade-video-title {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    font-weight: 700;
    color: #FFFFFF;
    margin: 0 0 6px;
    line-height: 1.35;
    text-shadow: 0 2px 6px rgba(0, 0, 0, 0.8);
}

.facade-video-sub {
    font-size: 0.85rem;
    color: rgba(255, 255, 255, 0.85);
    margin: 0;
}

/* Custom Play Overlay */
.video-play-overlay {
    position: absolute;
    inset: 0;
    background: linear-gradient(180deg, rgba(11, 30, 66, 0.25) 0%, rgba(11, 30, 66, 0.8) 100%);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 16px;
    cursor: pointer;
    transition: opacity 0.3s ease;
    z-index: 5;
}

.video-play-overlay.hidden {
    opacity: 0;
    pointer-events: none;
}

.play-pulse-btn {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--red) 0%, var(--red-hover) 100%);
    color: var(--ivory);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.75rem;
    box-shadow: 0 0 0 12px rgba(22, 143, 232, 0.28), 0 10px 30px rgba(0, 0, 0, 0.3);
    transition: transform 0.3s ease, background-color 0.3s ease;
}

.video-play-overlay:hover .play-pulse-btn {
    transform: scale(1.1);
    box-shadow: 0 0 0 16px rgba(22, 143, 232, 0.38), 0 14px 36px rgba(0, 0, 0, 0.4);
}

.play-label-text {
    font-family: var(--font-heading);
    font-size: 1.125rem;
    color: var(--ivory);
    letter-spacing: 0.05em;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.5);
}

.video-quote-box {
    text-align: center;
    max-width: 760px;
    margin: 0 auto;
}

.video-quote-text {
    font-family: var(--font-heading);
    font-size: 1.35rem;
    font-style: italic;
    color: var(--brown-dark);
    line-height: 1.7;
    margin-bottom: 28px;
    position: relative;
    padding: 0 20px;
}

/* ------------------------------------------------------------
   9. CHƯƠNG 2 — NHỮNG TRANG KÝ ỨC (COLLAGE ALBUM)
   ------------------------------------------------------------ */
.chapter-memory-section {
    background-color: var(--ivory);
}

.memory-grid-layout {
    display: flex;
    flex-direction: column;
    gap: 24px;
    margin-top: 48px;
}

.memory-row {
    display: grid;
    gap: 24px;
}

.memory-row-top {
    grid-template-columns: 1.42fr 1fr;
}

.memory-row-bottom {
    grid-template-columns: repeat(3, 1fr);
}

.memory-card {
    background: #FFFFFF;
    border-radius: 14px;
    overflow: hidden;
    border: 1px solid rgba(201, 154, 61, 0.28);
    box-shadow: 0 4px 18px rgba(74, 48, 40, 0.05);
    display: flex;
    flex-direction: column;
    transition: transform 0.35s ease, box-shadow 0.35s ease, border-color 0.35s ease;
}

.memory-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 28px rgba(74, 48, 40, 0.09);
    border-color: rgba(201, 154, 61, 0.5);
}

.memory-card-img-wrap {
    width: 100%;
    overflow: hidden;
    background-color: var(--cream);
    display: flex;
    align-items: center;
    justify-content: center;
}

.memory-row-top .memory-card-img-wrap {
    height: 310px;
}

.memory-row-bottom .memory-card-img-wrap {
    height: 250px;
}

.memory-card-img-wrap img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
    transition: transform 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

.memory-card:hover .memory-card-img-wrap img {
    transform: scale(1.035);
}

.memory-card-caption {
    padding: 16px 20px 20px;
    background: #FFFFFF;
}

.memory-card-caption h3 {
    font-family: var(--font-body);
    font-size: 1.05rem;
    font-weight: 500;
    color: #4A3E39;
    line-height: 1.4;
    letter-spacing: -0.01em;
}

/* Thẻ ghi âm ở giữa */
.memory-card-voice {
    background: #F9F3E7;
    border: 1px solid rgba(201, 154, 61, 0.35);
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 30px 20px;
}

.memory-voice-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 22px;
    height: 100%;
}

.memory-voice-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 4px;
    height: 30px;
}

.memory-voice-icon .v-bar {
    width: 3.5px;
    background-color: var(--red);
    border-radius: 2px;
}

.v-bar-1 {
    height: 12px;
}

.v-bar-2 {
    height: 26px;
}

.v-bar-3 {
    height: 16px;
}

.v-bar-4 {
    height: 30px;
}

.v-bar-5 {
    height: 14px;
}

.memory-voice-text {
    font-size: 0.95rem;
    color: #5C4D44;
    line-height: 1.6;
    font-weight: 500;
}

/* ------------------------------------------------------------
   10. CHƯƠNG 3 — CUỐN SÁCH SỐNG (MOCKUP SẢN PHẨM)
   ------------------------------------------------------------ */
.chapter-livings-section {
    background: linear-gradient(180deg, var(--paper-bg) 0%, var(--cream-light) 100%);
    border-top: 1px solid var(--gold-border);
    border-bottom: 1px solid var(--gold-border);
}

.living-book-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

/* Interactive UI Mockup */
.mockup-book-device {
    background: var(--ivory);
    border-radius: var(--radius-lg);
    border: 2px solid var(--gold-border);
    box-shadow: var(--shadow-book);
    overflow: hidden;
    position: relative;
}

.mockup-device-header {
    background: var(--brown-dark);
    color: var(--ivory);
    padding: 14px 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 0.8125rem;
}

.mockup-header-title {
    font-family: var(--font-heading);
    color: var(--gold-light);
    font-weight: 600;
    letter-spacing: 0.05em;
}

.mockup-header-actions {
    display: flex;
    gap: 8px;
}

.mockup-header-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--gold);
    opacity: 0.7;
}

.mockup-body {
    padding: 24px;
}

/* Tree Mini Visualization */
.tree-node-ancestor {
    background: var(--paper-bg);
    border: 1px solid var(--gold-border);
    border-radius: var(--radius-sm);
    padding: 16px;
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 16px;
}

.ancestor-avatar {
    width: 56px;
    height: 56px;
    border-radius: 50%;
    border: 2px solid var(--gold);
    object-fit: cover;
}

.ancestor-info h4 {
    font-size: 1.05rem;
    color: var(--brown-dark);
    margin-bottom: 2px;
}

.ancestor-info p {
    font-size: 0.8125rem;
    color: var(--text-muted);
}

/* Family Wisdom & Motto Card (Chương 3) */
.family-wisdom-card {
    background: linear-gradient(135deg, #FFFDF9 0%, #FAF4EB 100%);
    border-radius: var(--radius-sm);
    padding: 14px 18px;
    margin-bottom: 16px;
    border: 1px solid var(--gold-border);
    position: relative;
    box-shadow: 0 3px 12px rgba(184, 134, 11, 0.08);
    transition: var(--transition-smooth);
}

.family-wisdom-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(184, 134, 11, 0.16);
    border-color: var(--gold-dark);
}

.wisdom-card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 8px;
}

.wisdom-tag {
    font-family: var(--font-display, serif);
    font-weight: 700;
    font-size: 0.8125rem;
    color: var(--red);
    letter-spacing: 0.5px;
    text-transform: uppercase;
}

.wisdom-status-badge {
    font-size: 0.72rem;
    font-weight: 600;
    color: #15803D;
    background: rgba(22, 163, 74, 0.12);
    padding: 2px 8px;
    border-radius: 999px;
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

.wisdom-quote-text {
    font-family: var(--font-body, serif);
    font-style: italic;
    font-size: 0.9375rem;
    line-height: 1.55;
    color: var(--brown-dark);
    margin: 0 0 10px 0;
    padding-left: 12px;
    border-left: 3px solid var(--gold);
}

.wisdom-card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 8px;
    padding-top: 8px;
    border-top: 1px dashed rgba(184, 134, 11, 0.25);
    font-size: 0.775rem;
}

.wisdom-author {
    color: var(--text-muted);
    font-weight: 500;
}

.wisdom-gen-tag {
    color: var(--gold-dark);
    font-weight: 600;
}

/* Timeline Branch */
.mockup-timeline-row {
    display: flex;
    justify-content: space-between;
    padding-top: 12px;
    border-top: 1px dashed var(--gold-border);
    font-size: 0.75rem;
    color: var(--text-muted);
}

.timeline-year-tag {
    font-weight: 700;
    color: var(--red);
}

/* Right Editorial Story */
.living-book-narrative {
    display: flex;
    flex-direction: column;
    gap: 32px;
}

.narrative-timeline-steps {
    display: flex;
    flex-direction: column;
    gap: 20px;
    position: relative;
    padding-left: 28px;
    border-left: 2px solid var(--gold-border);
}

.timeline-step-item {
    position: relative;
}

.timeline-step-item::before {
    content: "";
    position: absolute;
    left: -34px;
    top: 6px;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background-color: var(--ivory);
    border: 2px solid var(--red);
}

.timeline-step-title {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--brown-dark);
    margin-bottom: 4px;
}

.timeline-step-desc {
    font-size: 0.95rem;
    color: var(--text-muted);
}

.living-flow-badge {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    padding: 10px 20px;
    background: var(--ivory);
    border: 1px solid var(--gold-border);
    border-radius: var(--radius-pill);
    font-weight: 600;
    font-size: 0.9375rem;
    color: var(--brown);
    box-shadow: var(--shadow-soft);
}

/* ------------------------------------------------------------
   11. CHƯƠNG 4 — TỪ GIA ĐÌNH ĐẾN MỘT CÂU CHUYỆN (4 BƯỚC HÀNH TRÌNH)
   ------------------------------------------------------------ */
.chapter-journey-section {
    background-color: var(--paper-bg);
    border-top: 1px solid var(--gold-border);
    border-bottom: 1px solid var(--gold-border);
}

/* Chapter 4 Interactive Showcase Touch Slider (Full Bleed) */
.journey-showcase-container {
    display: block;
    max-width: 1040px;
    margin: 40px auto 50px;
    width: 100%;
}

/* Slider Viewport */
.journey-slider-viewport {
    position: relative;
    overflow: hidden;
    border-radius: 20px;
    background: #071D36;
    border: 1.5px solid rgba(56, 189, 248, 0.45);
    box-shadow: 0 25px 60px rgba(10, 34, 64, 0.18);
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    touch-action: pan-y;
    width: 100%;
}

.slider-nav-btn {
    position: absolute;
    top: 45%;
    transform: translateY(-50%);
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: rgba(7, 29, 54, 0.85);
    border: 1.5px solid rgba(56, 189, 248, 0.5);
    color: var(--white);
    font-size: 1.2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    z-index: 10;
    transition: all 0.25s ease;
    backdrop-filter: blur(8px);
    box-shadow: 0 6px 18px rgba(0, 0, 0, 0.35);
}

.slider-nav-btn.prev {
    left: 16px;
}

.slider-nav-btn.next {
    right: 16px;
}

.slider-nav-btn:hover {
    background: var(--primary-blue);
    color: var(--white);
    border-color: var(--primary-blue);
    transform: translateY(-50%) scale(1.1);
}

.journey-slider-track {
    display: flex;
    width: 100%;
    transition: transform 0.45s cubic-bezier(0.25, 1, 0.5, 1);
    will-change: transform;
    cursor: grab;
    user-select: none;
}

.journey-slider-track.dragging {
    transition: none;
    cursor: grabbing;
}

.journey-slide-item {
    min-width: 100%;
    width: 100%;
    display: flex;
    flex-direction: column;
    padding: 0;
    margin: 0;
    box-sizing: border-box;
    flex-shrink: 0;
    background: #071D36;
    overflow: hidden;
}

.slide-device-frame {
    width: 100%;
    background: transparent;
    border: none;
    border-radius: 0;
    box-shadow: none;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    overflow: hidden;
    position: relative;
}

.slide-img-box {
    width: 100%;
    aspect-ratio: 1448 / 1086;
    display: block;
    background: #071D36;
    overflow: hidden;
    position: relative;
}

.slide-img-box img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: top center;
    display: block;
    pointer-events: none;
    border: none;
}

.slide-caption-bar {
    width: 100%;
    background: #071D36;
    color: var(--white);
    padding: 14px 24px;
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 0.95rem;
    border-top: 1px solid rgba(56, 189, 248, 0.2);
    box-sizing: border-box;
}

.caption-step {
    font-weight: 800;
    color: #38BDF8;
    letter-spacing: 0.05em;
    background: rgba(56, 189, 248, 0.2);
    border: 1px solid rgba(56, 189, 248, 0.4);
    padding: 3px 10px;
    border-radius: 7px;
    font-size: 0.8125rem;
    flex-shrink: 0;
}

.caption-text {
    color: #E2EEF9;
    font-weight: 600;
    font-size: 0.95rem;
    white-space: normal;
    overflow: visible;
    text-overflow: clip;
    line-height: 1.35;
    flex: 1;
    text-align: left;
}

/* Slider Pagination */
.journey-slider-pagination {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 28px;
    border-top: 1px solid rgba(56, 189, 248, 0.25);
    background: #05162B;
}

.slider-dots {
    display: flex;
    align-items: center;
    gap: 8px;
}

.slider-dots .dot {
    width: 10px;
    height: 10px;
    border-radius: 5px;
    background: rgba(255, 255, 255, 0.25);
    cursor: pointer;
    transition: all 0.3s ease;
    border: none;
    padding: 0;
}

.slider-dots .dot:hover {
    background: var(--primary-blue);
    transform: scale(1.2);
}

.slider-dots .dot.active {
    width: 28px;
    background: #38BDF8;
    box-shadow: 0 0 10px rgba(56, 189, 248, 0.6);
}

.slider-counter {
    font-family: var(--font-body);
    font-size: 0.875rem;
    font-weight: 700;
    color: #38BDF8;
    letter-spacing: 0.08em;
}

/* Journey Ending Statement */
.journey-bottom-statement {
    text-align: center;
    max-width: 680px;
    margin: 0 auto;
}

.journey-ending-text {
    font-family: var(--font-heading);
    font-size: 1.2rem;
    font-style: italic;
    color: var(--brown-dark);
    margin-bottom: 24px;
    line-height: 1.6;
}

.btn-journey-cta {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 34px;
    font-size: 1.05rem;
}

.btn-journey-cta .btn-arrow {
    transition: transform 0.3s ease;
}

.btn-journey-cta:hover .btn-arrow {
    transform: translateX(4px);
}

/* ------------------------------------------------------------
   13. CHƯƠNG 6 — CUỐN SÁCH ĐƯỢC TRAO ĐI (AUDIENCE)
   ------------------------------------------------------------ */
.chapter-audience-section {
    background-color: var(--ivory);
}

.audience-cards-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
    margin-bottom: 50px;
}

.audience-card {
    position: relative;
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-card);
    border: 1px solid var(--gold-border);
    background: var(--brown-dark);
    height: 420px;
    cursor: pointer;
}

.audience-bg-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    opacity: 0.85;
    transition: transform 0.6s ease, opacity 0.6s ease;
}

.audience-card:hover .audience-bg-img {
    transform: scale(1.06);
    opacity: 0.45;
}

.audience-overlay-content {
    position: absolute;
    inset: 0;
    background: linear-gradient(180deg, rgba(47, 30, 25, 0.1) 0%, rgba(47, 30, 25, 0.85) 100%);
    padding: 32px 24px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    color: var(--ivory);
    transition: background 0.4s ease;
}

.audience-card:hover .audience-overlay-content {
    background: rgba(47, 30, 25, 0.88);
}

.audience-tag {
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.15em;
    color: var(--gold-light);
    text-transform: uppercase;
    margin-bottom: 8px;
    opacity: 1;
    display: block;
}

.audience-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--ivory);
    margin-bottom: 0;
    transition: margin-bottom 0.35s ease;
}

.audience-desc-short {
    font-size: 1rem;
    color: var(--cream);
    line-height: 1.5;
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transform: translateY(8px);
    transition: max-height 0.4s ease, opacity 0.4s ease, margin-top 0.4s ease, transform 0.4s ease;
}

.audience-detail-expand {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transform: translateY(8px);
    transition: max-height 0.4s ease, opacity 0.4s ease, margin-top 0.4s ease, padding-top 0.4s ease, transform 0.4s ease;
    font-size: 0.875rem;
    color: var(--ivory);
    line-height: 1.6;
    border-top: 1px dashed var(--gold-border);
}

.audience-card:hover .audience-title,
.audience-card.expanded .audience-title,
.audience-card:focus .audience-title {
    margin-bottom: 6px;
}

.audience-card:hover .audience-desc-short,
.audience-card.expanded .audience-desc-short,
.audience-card:focus .audience-desc-short {
    max-height: 100px;
    opacity: 1;
    margin-top: 6px;
    transform: translateY(0);
}

.audience-card:hover .audience-detail-expand,
.audience-card.expanded .audience-detail-expand,
.audience-card:focus .audience-detail-expand {
    max-height: 160px;
    opacity: 1;
    margin-top: 12px;
    padding-top: 12px;
    transform: translateY(0);
}

/* ------------------------------------------------------------
   13. CHƯƠNG 6 — KHUYẾN HỌC VÀ ĐẠO HIẾU (TÍCH ĐIỂM ĐỔI QUÀ)
   ------------------------------------------------------------ */
.chapter-reward-section {
    background: linear-gradient(180deg, #F8FAFD 0%, #EFF6FC 50%, #F8FAFD 100%);
    border-top: 1px solid rgba(56, 189, 248, 0.3);
    border-bottom: 1px solid rgba(56, 189, 248, 0.3);
    position: relative;
    overflow: hidden;
}

.chapter-reward-section,
.chapter-reward-section * {
    box-sizing: border-box;
}

/* Rate Badge */
.reward-rate-badge {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    gap: 8px;
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.15) 0%, rgba(22, 143, 232, 0.12) 100%);
    border: 1.5px solid rgba(245, 158, 11, 0.4);
    color: #B45309;
    padding: 8px 20px;
    border-radius: var(--radius-pill);
    font-size: 0.875rem;
    font-weight: 700;
    letter-spacing: 0.03em;
    margin-bottom: 18px;
    box-shadow: 0 4px 14px rgba(245, 158, 11, 0.12);
    max-width: 100%;
    text-align: center;
    word-break: break-word;
    overflow-wrap: break-word;
}

.reward-rate-badge strong {
    color: #D97706;
}

/* ------------------------------------------------------------
   CHƯƠNG 6 — 4 CỘT TRỤ ĐỘT PHÁ (VISUAL CARDS THEO PHONG CÁCH CHƯƠNG 5)
   ------------------------------------------------------------ */
.hieu-hoc-pillars-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 24px;
    margin-top: 36px;
    margin-bottom: 44px;
    width: 100%;
}

.hieu-hoc-pillar-card {
    position: relative;
    border-radius: var(--radius-md, 20px);
    overflow: hidden;
    box-shadow: 0 12px 36px rgba(10, 34, 64, 0.1);
    border: 1.5px solid rgba(56, 189, 248, 0.35);
    background: #0A2240;
    height: 400px;
    cursor: pointer;
    transition: transform 0.4s cubic-bezier(0.2, 0, 0.2, 1), border-color 0.4s ease, box-shadow 0.4s ease;
    will-change: transform;
    transform: translateZ(0);
    outline: none;
}

.pillar-bg-img {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    opacity: 1;
    filter: none;
    transition: transform 0.6s cubic-bezier(0.2, 0, 0.2, 1);
}

.hieu-hoc-pillar-card:hover,
.hieu-hoc-pillar-card:focus-within,
.hieu-hoc-pillar-card.is-active {
    transform: translateY(-8px) translateZ(0);
    border-color: var(--primary-blue, #168FE8);
    box-shadow: 0 24px 50px rgba(22, 143, 232, 0.25);
}

.hieu-hoc-pillar-card:hover .pillar-bg-img,
.hieu-hoc-pillar-card:focus-within .pillar-bg-img,
.hieu-hoc-pillar-card.is-active .pillar-bg-img {
    transform: scale(1.05);
    opacity: 1;
    filter: none;
}

.pillar-overlay-content {
    position: absolute;
    inset: 0;
    background: linear-gradient(180deg, transparent 0%, rgba(10, 34, 64, 0.1) 35%, rgba(10, 34, 64, 0.72) 70%, rgba(10, 34, 64, 0.92) 100%);
    padding: 24px 20px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    color: #FFFFFF;
    transition: background 0.4s ease;
}

.hieu-hoc-pillar-card:hover .pillar-overlay-content,
.hieu-hoc-pillar-card:focus-within .pillar-overlay-content,
.hieu-hoc-pillar-card.is-active .pillar-overlay-content {
    background: linear-gradient(180deg, transparent 0%, rgba(10, 34, 64, 0.2) 30%, rgba(10, 34, 64, 0.78) 65%, rgba(10, 34, 64, 0.95) 100%);
}

.pillar-meta-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 8px;
    margin-bottom: 8px;
    flex-wrap: wrap;
}

.pillar-tag {
    font-size: 0.6875rem;
    font-weight: 800;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    padding: 4px 8px;
    border-radius: 6px;
    display: inline-block;
}

.pillar-tag.gold {
    background: rgba(245, 158, 11, 0.3);
    color: #FDE68A;
    border: 1px solid rgba(245, 158, 11, 0.6);
}

.pillar-tag.blue {
    background: rgba(22, 143, 232, 0.3);
    color: #BAE6FD;
    border: 1px solid rgba(56, 189, 248, 0.6);
}

.pillar-tag.red {
    background: rgba(239, 68, 68, 0.3);
    color: #FECACA;
    border: 1px solid rgba(239, 68, 68, 0.6);
}

.pillar-tag.emerald {
    background: rgba(16, 185, 129, 0.3);
    color: #A7F3D0;
    border: 1px solid rgba(16, 185, 129, 0.6);
}

.pillar-rate-pill {
    font-size: 0.72rem;
    font-weight: 700;
    padding: 3px 8px;
    border-radius: 9999px;
    background: rgba(10, 34, 64, 0.65);
    color: #FFFFFF;
    border: 1px solid rgba(255, 255, 255, 0.3);
}

.pillar-title {
    font-size: 1.28rem;
    font-weight: 700;
    color: #FFFFFF;
    margin-bottom: 0;
    line-height: 1.3;
    text-shadow: 0 2px 6px rgba(0, 0, 0, 0.7);
    transition: margin-bottom 0.35s ease;
}

.hieu-hoc-pillar-card:hover .pillar-title,
.hieu-hoc-pillar-card:focus-within .pillar-title,
.hieu-hoc-pillar-card.is-active .pillar-title {
    margin-bottom: 6px;
}

.pillar-desc-short {
    font-size: 0.875rem;
    color: #E2E8F0;
    line-height: 1.45;
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transform: translateY(6px);
    transition: max-height 0.4s ease, opacity 0.4s ease, margin-top 0.4s ease, transform 0.4s ease;
    margin: 0;
}

.pillar-detail-expand {
    font-size: 0.8125rem;
    color: #CBD5E1;
    line-height: 1.55;
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transform: translateY(6px);
    border-top: 1px dashed rgba(255, 255, 255, 0.25);
    transition: max-height 0.4s ease, opacity 0.4s ease, margin-top 0.4s ease, padding-top 0.4s ease, transform 0.4s ease;
}

.hieu-hoc-pillar-card:hover .pillar-desc-short,
.hieu-hoc-pillar-card:focus-within .pillar-desc-short,
.hieu-hoc-pillar-card.is-active .pillar-desc-short {
    max-height: 90px;
    opacity: 1;
    margin-top: 6px;
    transform: translateY(0);
}

.hieu-hoc-pillar-card:hover .pillar-detail-expand,
.hieu-hoc-pillar-card:focus-within .pillar-detail-expand,
.hieu-hoc-pillar-card.is-active .pillar-detail-expand {
    max-height: 140px;
    opacity: 1;
    margin-top: 10px;
    padding-top: 10px;
    transform: translateY(0);
}

/* ------------------------------------------------------------
   CHƯƠNG 6 — QUY TRÌNH 4 BƯỚC GẮN KẾT (VISUAL FLOW THEO PHONG CÁCH CHƯƠNG 5)
   ------------------------------------------------------------ */
.hieu-hoc-flow-box {
    background: #FFFFFF;
    border-radius: 24px;
    border: 1.5px solid rgba(56, 189, 248, 0.3);
    padding: 32px 28px;
    box-shadow: 0 16px 40px rgba(10, 34, 64, 0.06);
    margin-bottom: 50px;
    width: 100%;
    overflow-wrap: break-word;
    word-break: break-word;
}

.flow-header {
    text-align: center;
    margin-bottom: 28px;
}

.flow-pre-tag {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 800;
    letter-spacing: 0.08em;
    color: var(--primary-blue);
    background: rgba(22, 143, 232, 0.1);
    padding: 4px 14px;
    border-radius: var(--radius-pill);
    margin-bottom: 8px;
    max-width: 100%;
    overflow-wrap: break-word;
}

.flow-title {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--brown-dark);
    margin-bottom: 6px;
    overflow-wrap: break-word;
    word-break: break-word;
}

.flow-desc {
    font-size: 0.925rem;
    color: var(--text-muted);
    margin: 0;
    overflow-wrap: break-word;
    word-break: break-word;
}

.flow-steps-track {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    width: 100%;
}

.flow-step-node {
    flex: 1;
    position: relative;
    border-radius: 18px;
    overflow: hidden;
    height: 310px;
    box-shadow: 0 10px 28px rgba(10, 34, 64, 0.08);
    border: 1.5px solid rgba(56, 189, 248, 0.28);
    background: #0A2240;
    cursor: pointer;
    transition: transform 0.4s ease, border-color 0.4s ease, box-shadow 0.4s ease;
    will-change: transform;
    transform: translateZ(0);
    outline: none;
    min-width: 0;
}

.node-bg-img {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    opacity: 1;
    filter: none;
    transition: transform 0.6s cubic-bezier(0.2, 0, 0.2, 1);
}

.flow-step-node:hover,
.flow-step-node:focus-within,
.flow-step-node.is-active {
    transform: translateY(-6px) translateZ(0);
    border-color: var(--primary-blue);
    box-shadow: 0 18px 40px rgba(22, 143, 232, 0.22);
}

.flow-step-node:hover .node-bg-img,
.flow-step-node:focus-within .node-bg-img,
.flow-step-node.is-active .node-bg-img {
    transform: scale(1.05);
    opacity: 1;
    filter: none;
}

.node-overlay-content {
    position: absolute;
    inset: 0;
    background: linear-gradient(180deg, transparent 0%, rgba(10, 34, 64, 0.1) 35%, rgba(10, 34, 64, 0.72) 70%, rgba(10, 34, 64, 0.92) 100%);
    padding: 20px 16px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    color: #FFFFFF;
    text-align: left;
    transition: background 0.4s ease;
}

.flow-step-node:hover .node-overlay-content,
.flow-step-node:focus-within .node-overlay-content,
.flow-step-node.is-active .node-overlay-content {
    background: linear-gradient(180deg, transparent 0%, rgba(10, 34, 64, 0.2) 30%, rgba(10, 34, 64, 0.78) 65%, rgba(10, 34, 64, 0.95) 100%);
}

.node-num {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary-blue) 0%, #0284C7 100%);
    color: #FFFFFF;
    font-weight: 800;
    font-size: 0.8125rem;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 14px rgba(22, 143, 232, 0.4);
    margin-bottom: 8px;
    flex-shrink: 0;
}

.node-title {
    font-size: 1.05rem;
    font-weight: 700;
    color: #FFFFFF;
    margin-bottom: 0;
    line-height: 1.3;
    transition: margin-bottom 0.35s ease;
}

.flow-step-node:hover .node-title,
.flow-step-node:focus-within .node-title,
.flow-step-node.is-active .node-title {
    margin-bottom: 4px;
}

.node-desc-short {
    font-size: 0.8rem;
    color: #E2E8F0;
    line-height: 1.4;
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transform: translateY(6px);
    transition: max-height 0.4s ease, opacity 0.4s ease, margin-top 0.4s ease, transform 0.4s ease;
    margin: 0;
}

.node-detail-expand {
    font-size: 0.775rem;
    color: #CBD5E1;
    line-height: 1.45;
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transform: translateY(6px);
    border-top: 1px dashed rgba(255, 255, 255, 0.25);
    transition: max-height 0.4s ease, opacity 0.4s ease, margin-top 0.4s ease, padding-top 0.4s ease, transform 0.4s ease;
}

.flow-step-node:hover .node-desc-short,
.flow-step-node:focus-within .node-desc-short,
.flow-step-node.is-active .node-desc-short {
    max-height: 80px;
    opacity: 1;
    margin-top: 4px;
    transform: translateY(0);
}

.flow-step-node:hover .node-detail-expand,
.flow-step-node:focus-within .node-detail-expand,
.flow-step-node.is-active .node-detail-expand {
    max-height: 120px;
    opacity: 1;
    margin-top: 8px;
    padding-top: 8px;
    transform: translateY(0);
}

.flow-step-connector {
    font-size: 1.4rem;
    color: var(--primary-blue);
    flex-shrink: 0;
    opacity: 0.7;
}

/* Bảng Tra Cứu Điểm Thưởng Tương Tác (3-Tab Table) */
.reward-lookup-section {
    background: #FFFFFF;
    border-radius: 24px;
    border: 1.5px solid rgba(56, 189, 248, 0.32);
    padding: 32px 28px;
    box-shadow: 0 16px 40px rgba(10, 34, 64, 0.07);
    margin-bottom: 50px;
    width: 100%;
    overflow-wrap: break-word;
    word-break: break-word;
}

.lookup-header-center {
    text-align: center;
    margin-bottom: 24px;
}

.lookup-main-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--brown-dark);
    margin-top: 6px;
    margin-bottom: 6px;
    overflow-wrap: break-word;
    word-break: break-word;
}

.lookup-sub-desc {
    font-size: 0.925rem;
    color: var(--text-muted);
    overflow-wrap: break-word;
    word-break: break-word;
}

.reward-tab-nav {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-bottom: 24px;
    flex-wrap: wrap;
    width: 100%;
}

.reward-tab-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px 20px;
    border-radius: var(--radius-pill);
    background: #F1F6FC;
    border: 1.5px solid rgba(56, 189, 248, 0.3);
    font-size: 0.925rem;
    font-weight: 700;
    color: var(--brown-dark);
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.2, 0, 0.2, 1);
    max-width: 100%;
    overflow-wrap: break-word;
    word-break: break-word;
}

.reward-tab-btn:hover {
    background: #E5F1FC;
    border-color: var(--primary-blue);
    transform: translateY(-2px);
}

.reward-tab-btn.active {
    background: linear-gradient(135deg, var(--primary-blue) 0%, #0B6AC1 100%);
    color: #FFFFFF;
    border-color: var(--primary-blue);
    box-shadow: 0 6px 20px rgba(22, 143, 232, 0.35);
}

.reward-tab-btn.active .tab-btn-icon {
    transform: scale(1.15);
}

.reward-tab-panel {
    display: none;
    animation: fadeIn 0.35s ease forwards;
    width: 100%;
}

.reward-tab-panel.active {
    display: block;
}

.reward-teacher-guide,
.reward-parent-guide {
    background: linear-gradient(135deg, rgba(22, 143, 232, 0.08) 0%, rgba(245, 158, 11, 0.06) 100%);
    border: 1px solid rgba(56, 189, 248, 0.3);
    border-left: 4px solid var(--primary-blue);
    border-radius: 12px;
    padding: 14px 18px;
    margin-bottom: 20px;
    width: 100%;
    overflow-wrap: break-word;
    word-break: break-word;
}

.reward-parent-guide {
    border-left-color: var(--gold);
}

.teacher-note,
.parent-note {
    font-size: 0.9rem;
    color: var(--text-dark);
    line-height: 1.55;
    margin: 0;
    overflow-wrap: break-word;
    word-break: break-word;
}

.reward-table-responsive {
    width: 100%;
    border-radius: 18px;
    border: 1px solid rgba(56, 189, 248, 0.25);
    background: #FFFFFF;
    box-shadow: 0 4px 16px rgba(10, 34, 64, 0.04);
}

.reward-data-table {
    width: 100%;
    border-collapse: collapse;
    text-align: left;
    font-size: 0.925rem;
}

.reward-data-table thead th:nth-child(1),
.reward-data-table tbody td:nth-child(1) {
    width: 32%;
}

.reward-data-table thead th:nth-child(2),
.reward-data-table tbody td:nth-child(2) {
    width: 38%;
}

.reward-data-table thead th:nth-child(3),
.reward-data-table tbody td:nth-child(3) {
    width: 16%;
}

.reward-data-table thead th:nth-child(4),
.reward-data-table tbody td:nth-child(4) {
    width: 14%;
    text-align: right;
}

.reward-data-table th,
.reward-data-table td {
    padding: 14px 16px;
    border-bottom: 1px solid rgba(56, 189, 248, 0.15);
    overflow-wrap: break-word;
    word-break: break-word;
}

.reward-data-table thead th {
    background: #F2F7FC;
    color: var(--brown-dark);
    font-weight: 700;
    font-size: 0.85rem;
    letter-spacing: 0.03em;
    text-transform: uppercase;
    border-bottom: 2px solid rgba(56, 189, 248, 0.3);
}

.reward-data-table tbody tr:last-child td {
    border-bottom: none;
}

.reward-data-table tbody tr {
    transition: background-color 0.2s ease;
}

.reward-data-table tbody tr:hover {
    background: #F8FBFE;
}

.point-badge {
    display: inline-block;
    padding: 4px 10px;
    border-radius: var(--radius-pill);
    font-size: 0.825rem;
    font-weight: 700;
    background: rgba(22, 143, 232, 0.12);
    color: var(--primary-blue);
    border: 1px solid rgba(56, 189, 248, 0.4);
    text-align: center;
    max-width: 100%;
    overflow-wrap: break-word;
    word-break: break-word;
}

.point-badge.gold {
    background: rgba(245, 158, 11, 0.14);
    color: #B45309;
    border-color: rgba(245, 158, 11, 0.4);
}

.point-badge.blue {
    background: rgba(22, 143, 232, 0.14);
    color: #09599E;
    border-color: rgba(56, 189, 248, 0.5);
}

.point-badge.emerald {
    background: rgba(16, 185, 129, 0.14);
    color: #059669;
    border-color: rgba(16, 185, 129, 0.4);
}

.vnd-val {
    font-weight: 700;
    color: var(--brown-dark);
    font-size: 0.875rem;
    max-width: 100%;
    overflow-wrap: break-word;
    word-break: break-word;
}

.vnd-val.gold {
    color: #B45309;
}

.vnd-val.emerald {
    color: #059669;
}

/* 2 Showcase Cards */
.reward-grid-showcase {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 28px;
    margin-bottom: 40px;
    width: 100%;
}

.reward-showcase-card {
    background: #FFFFFF;
    border-radius: 24px;
    border: 1.5px solid rgba(56, 189, 248, 0.28);
    box-shadow: 0 16px 40px rgba(10, 34, 64, 0.08);
    padding: 30px 26px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    transition: all 0.4s cubic-bezier(0.2, 0, 0.2, 1);
    position: relative;
    min-width: 0;
    overflow-wrap: break-word;
    word-break: break-word;
}

.reward-showcase-card:hover {
    transform: translateY(-6px);
    border-color: var(--primary-blue);
    box-shadow: 0 24px 50px rgba(22, 143, 232, 0.16);
}

.reward-badge-tag {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 6px 14px;
    border-radius: var(--radius-pill);
    font-size: 0.8125rem;
    font-weight: 700;
    letter-spacing: 0.04em;
    margin-bottom: 14px;
    max-width: 100%;
    overflow-wrap: break-word;
}

.reward-badge-tag.gold-tag {
    background: rgba(245, 158, 11, 0.12);
    color: #B45309;
    border: 1px solid rgba(245, 158, 11, 0.3);
}

.reward-badge-tag.blue-tag {
    background: rgba(22, 143, 232, 0.12);
    color: var(--primary-blue);
    border: 1px solid rgba(56, 189, 248, 0.35);
}

.reward-card-title {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--brown-dark);
    margin-bottom: 10px;
    line-height: 1.3;
    overflow-wrap: break-word;
    word-break: break-word;
}

.reward-card-desc {
    font-size: 0.925rem;
    color: var(--text-muted);
    line-height: 1.55;
    margin-bottom: 18px;
    overflow-wrap: break-word;
    word-break: break-word;
}

.reward-img-frame {
    width: 100%;
    height: 260px;
    border-radius: 18px;
    overflow: hidden;
    background: #0A2240;
    position: relative;
    margin-bottom: 22px;
    box-shadow: 0 8px 24px rgba(10, 34, 64, 0.12);
    border: 1px solid rgba(56, 189, 248, 0.2);
}

.reward-feature-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
    transition: transform 0.6s ease;
    display: block;
}

.reward-showcase-card:hover .reward-feature-img {
    transform: scale(1.04);
}

.reward-floating-pill {
    position: absolute;
    bottom: 12px;
    right: 12px;
    background: rgba(10, 34, 64, 0.92);
    border: 1px solid rgba(245, 158, 11, 0.5);
    border-radius: var(--radius-pill);
    padding: 6px 14px;
    display: flex;
    align-items: center;
    gap: 8px;
    color: #FDE68A;
    font-size: 0.78125rem;
    font-weight: 700;
    backdrop-filter: blur(8px);
    box-shadow: 0 4px 14px rgba(0, 0, 0, 0.3);
    max-width: calc(100% - 24px);
    overflow-wrap: break-word;
}

.reward-floating-pill.blue-pill {
    border-color: rgba(56, 189, 248, 0.5);
    color: #38BDF8;
}

.reward-features-list {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    flex-direction: column;
    gap: 12px;
    width: 100%;
}

.reward-features-list li {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    font-size: 0.8875rem;
    line-height: 1.5;
    color: var(--text-dark);
    min-width: 0;
    overflow-wrap: break-word;
    word-break: break-word;
}

.feature-check {
    width: 22px;
    height: 22px;
    border-radius: 50%;
    background: rgba(22, 143, 232, 0.12);
    color: var(--primary-blue);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 800;
    font-size: 0.8rem;
    flex-shrink: 0;
    margin-top: 1px;
}

/* Bottom CTA & Privacy Statement */
.reward-bottom-cta-wrap {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 18px;
    margin-top: 20px;
    width: 100%;
}

.reward-privacy-note {
    display: flex;
    align-items: center;
    gap: 10px;
    background: rgba(22, 143, 232, 0.07);
    border: 1px solid rgba(56, 189, 248, 0.28);
    border-radius: 12px;
    padding: 12px 18px;
    font-size: 0.85rem;
    color: var(--text-muted);
    line-height: 1.5;
    width: 100%;
    max-width: 820px;
    text-align: left;
    overflow-wrap: break-word;
    word-break: break-word;
}

.privacy-icon {
    font-size: 1.3rem;
    flex-shrink: 0;
}

.btn-reward-main {
    padding: 14px 32px;
    font-size: 1.025rem;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    max-width: 100%;
    text-align: center;
    overflow-wrap: break-word;
}

/* ------------------------------------------------------------
   14. CHƯƠNG CUỐI — GÌN GIỮ BẰNG NIỀM TIN (FORM & PRINCIPLES)
   ------------------------------------------------------------ */
.chapter-final-section {
    background: linear-gradient(180deg, var(--paper-bg) 0%, var(--cream-light) 100%);
    border-top: 1px solid var(--gold-border);
}

.final-grid-layout {
    display: grid;
    grid-template-columns: 1fr 1.05fr;
    gap: 60px;
    align-items: center;
}

/* Left Principles */
.principles-col {
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.principles-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.principle-item {
    display: flex;
    align-items: flex-start;
    gap: 16px;
    background: var(--ivory);
    padding: 18px 20px;
    border-radius: var(--radius-sm);
    border: 1px solid var(--gold-border);
    box-shadow: var(--shadow-soft);
}

.principle-icon {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--cream);
    color: var(--red);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.125rem;
    flex-shrink: 0;
}

.principle-text h4 {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--brown-dark);
    margin-bottom: 4px;
}

.principle-text p {
    font-size: 0.875rem;
    color: var(--text-muted);
}

/* Final Couplet Signature (Di sản & Đạo hiếu) */
.couplet-box {
    margin-top: 24px;
    padding: 24px 28px;
    background: linear-gradient(135deg, #071E38 0%, #0A2F59 50%, #06182E 100%);
    background-image: 
        radial-gradient(circle at 15% 20%, rgba(56, 189, 248, 0.18) 0%, transparent 45%),
        radial-gradient(circle at 85% 80%, rgba(245, 158, 11, 0.16) 0%, transparent 45%),
        linear-gradient(135deg, #071E38 0%, #0A2F59 50%, #06182E 100%);
    border: 1.5px solid rgba(245, 158, 11, 0.45);
    border-radius: var(--radius-md);
    box-shadow: 
        0 14px 35px rgba(7, 30, 56, 0.22),
        inset 0 0 25px rgba(56, 189, 248, 0.08);
    position: relative;
    overflow: hidden;
    text-align: center;
}

.couplet-ornament {
    font-size: 0.8125rem;
    color: var(--gold);
    letter-spacing: 0.35em;
    margin-bottom: 8px;
    opacity: 0.9;
    text-shadow: 0 0 10px rgba(245, 158, 11, 0.5);
}

.couplet-line {
    font-family: 'Lora', 'Playfair Display', Georgia, serif;
    font-style: italic;
    font-size: 1.25rem;
    font-weight: 500;
    color: #F1F6FC;
    line-height: 1.65;
    letter-spacing: 0.01em;
    margin: 4px 0;
}

.couplet-quote {
    font-family: 'Playfair Display', Georgia, serif;
    color: var(--gold);
    font-size: 1.45rem;
    font-style: normal;
    display: inline-block;
}

.couplet-em {
    font-style: normal;
    font-weight: 700;
    position: relative;
}

.couplet-em.gold-em {
    color: #FDE68A;
    text-shadow: 0 0 12px rgba(245, 158, 11, 0.6);
}

.couplet-em.blue-em {
    color: #38BDF8;
    text-shadow: 0 0 12px rgba(56, 189, 248, 0.7);
}

/* Right Consultation Form */
.form-card-container {
    background: var(--ivory);
    border-radius: var(--radius-md);
    border: 1px solid var(--gold-border);
    box-shadow: var(--shadow-book);
    padding: 40px 36px;
    position: relative;
}

.form-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--brown-dark);
    margin-bottom: 8px;
    text-align: center;
}

.form-sub {
    font-size: 0.9375rem;
    color: var(--text-muted);
    text-align: center;
    margin-bottom: 28px;
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.form-label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--brown-dark);
}

.form-input,
.form-select {
    width: 100%;
    padding: 13px 16px;
    border-radius: var(--radius-sm);
    border: 1px solid var(--gold-border);
    background-color: var(--paper-bg);
    color: var(--text);
    transition: var(--transition-snappy);
}

.form-input:focus,
.form-select:focus {
    outline: none;
    border-color: var(--red);
    background-color: var(--ivory);
    box-shadow: 0 0 0 3px var(--red-subtle);
}

.form-input.error,
.form-select.error {
    border-color: var(--red);
    background-color: #FFF5F5;
}

.form-error-msg {
    font-size: 0.75rem;
    color: var(--red);
    display: none;
}

.form-error-msg.visible {
    display: block;
}

/* Form States */
.form-loading-spinner {
    display: none;
    width: 20px;
    height: 20px;
    border: 2px solid var(--ivory);
    border-top-color: transparent;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

.contact-form.is-loading .btn-submit-text {
    display: none;
}

.contact-form.is-loading .form-loading-spinner {
    display: inline-block;
}

.form-success-box {
    display: none;
    text-align: center;
    padding: 30px 20px;
    background: var(--cream);
    border-radius: var(--radius-sm);
    border: 1px solid var(--gold-border);
}

.form-success-box.visible {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
    animation: fadeIn 0.4s ease;
}

.success-icon-badge {
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: var(--red);
    color: var(--ivory);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
}

.success-title {
    font-size: 1.35rem;
    font-weight: 700;
    color: var(--brown-dark);
}

.success-desc {
    font-size: 0.95rem;
    color: var(--text-muted);
    line-height: 1.6;
}

/* ------------------------------------------------------------
   15. FOOTER
   ------------------------------------------------------------ */
.site-footer {
    background-color: var(--brown-dark);
    color: var(--ivory);
    padding-top: 80px;
    padding-bottom: 40px;
    border-top: 4px solid var(--gold);
}

.footer-top-grid {
    display: grid;
    grid-template-columns: 1.5fr 1fr 1fr;
    gap: 50px;
    margin-bottom: 60px;
}

.footer-brand-col {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.site-footer .logo-main-title {
    font-family: 'Charm', 'Dancing Script', cursive, var(--font-heading);
    font-size: 1.95rem;
    font-weight: 400;
    color: #FDE68A; /* Màu vàng kim sáng thanh nhã */
    line-height: 1.05;
    letter-spacing: 0.02em;
    text-shadow: 0 1px 4px rgba(245, 158, 11, 0.35);
}

.site-footer .logo-sub-title {
    color: #38BDF8;
    font-weight: 700;
}

.footer-company-name {
    font-size: 1.125rem;
    font-weight: 700;
    letter-spacing: 0.05em;
    color: var(--gold-light);
}

.footer-address {
    font-size: 0.9375rem;
    color: var(--cream);
    line-height: 1.6;
    font-style: normal;
}

.footer-slogan {
    font-family: var(--font-heading);
    font-style: italic;
    font-size: 1rem;
    color: var(--gold);
    border-left: 2px solid var(--gold);
    padding-left: 12px;
    margin-top: 6px;
}

.footer-links-col h4 {
    color: var(--gold-light);
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 20px;
    letter-spacing: 0.05em;
}

.footer-nav-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.footer-nav-list a {
    color: var(--cream);
    font-size: 0.9375rem;
}

.footer-nav-list a:hover {
    color: var(--gold-light);
    padding-left: 4px;
}

.footer-bottom-bar {
    border-top: 1px solid rgba(201, 154, 61, 0.2);
    padding-top: 30px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 0.8125rem;
    color: var(--text-light);
}

/* ------------------------------------------------------------
   16. VIDEO MODAL (MOBILE & DESKTOP ENHANCEMENT)
   ------------------------------------------------------------ */
.video-modal {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.85);
    backdrop-filter: blur(8px);
    z-index: 2000;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
}

.video-modal.active {
    opacity: 1;
    visibility: visible;
}

.video-modal-inner {
    position: relative;
    width: 100%;
    max-width: 900px;
    aspect-ratio: 16 / 9;
    background: #000;
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.5);
}

.video-modal-close {
    position: absolute;
    top: -40px;
    right: 0;
    color: #fff;
    font-size: 1.75rem;
    cursor: pointer;
    background: none;
    border: none;
}

/* ------------------------------------------------------------
   17. SCROLL REVEAL ANIMATIONS
   ------------------------------------------------------------ */
.reveal {
    opacity: 0;
    transform: translateY(28px);
    transition: opacity 0.7s cubic-bezier(0.16, 1, 0.3, 1), transform 0.7s cubic-bezier(0.16, 1, 0.3, 1);
    will-change: opacity, transform;
}

.reveal.revealed {
    opacity: 1;
    transform: translateY(0);
}

.reveal-delay-1 {
    transition-delay: 0.15s;
}

.reveal-delay-2 {
    transition-delay: 0.3s;
}

.reveal-delay-3 {
    transition-delay: 0.45s;
}

@keyframes gentleFloat {

    0%,
    100% {
        transform: translateY(0);
    }

    50% {
        transform: translateY(-8px);
    }
}

@keyframes floatGlow {

    0%,
    100% {
        transform: translateY(0);
        box-shadow: 0 10px 25px rgba(152, 43, 43, 0.35);
    }

    50% {
        transform: translateY(-4px);
        box-shadow: 0 14px 30px rgba(152, 43, 43, 0.5);
    }
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: scale(0.96);
    }

    to {
        opacity: 1;
        transform: scale(1);
    }
}

/* ------------------------------------------------------------
   17B. ĐIỂM CHẠM TƯƠNG TÁC (INTERACTIVE TOUCHPOINTS)
   ------------------------------------------------------------ */

/* Chapter 1 View Tabs */
.chapter-view-tabs {
    display: flex;
    justify-content: center;
    gap: 14px;
    margin-bottom: 24px;
}

.tab-btn {
    background: var(--white);
    border: 1.5px solid var(--gold-border);
    color: var(--brown-dark);
    padding: 10px 22px;
    border-radius: 30px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    box-shadow: 0 4px 12px rgba(74, 48, 40, 0.05);
}

.tab-btn:hover {
    border-color: var(--gold);
    color: var(--red);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(152, 43, 43, 0.12);
}

.tab-btn.active {
    background: var(--red);
    border-color: var(--red);
    color: var(--white);
    box-shadow: 0 6px 20px rgba(152, 43, 43, 0.28);
}

/* ------------------------------------------------------------
   Chapter 1 Separated Blocks & Full Parchment Letter (7 Sections)
   ------------------------------------------------------------ */
.section-sub-desc {
    font-size: 1.05rem;
    color: var(--text-muted);
    max-width: 780px;
    margin: 12px auto 0;
    line-height: 1.65;
}

.chapter-part-block {
    margin-bottom: 70px;
}

.chapter-part-block:last-child {
    margin-bottom: 0;
}

.part-header-tag {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    background: rgba(22, 143, 232, 0.1);
    border: 1px solid rgba(22, 143, 232, 0.28);
    padding: 8px 20px;
    border-radius: var(--radius-pill);
    font-size: 0.8125rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    color: var(--primary-dark);
    margin-bottom: 24px;
    text-transform: uppercase;
}

.part-icon {
    font-size: 1.05rem;
}

/* Handwritten / Heritage Parchment Letter Paper */
.parchment-letter-wrapper {
    max-width: 920px;
    margin: 0 auto;
    animation: fadeIn 0.5s ease;
}

.parchment-letter-paper {
    background: #FFFCF7;
    background-image:
        radial-gradient(circle at 95% 5%, rgba(245, 158, 11, 0.08) 0, transparent 45%),
        radial-gradient(circle at 5% 95%, rgba(22, 143, 232, 0.06) 0, transparent 45%);
    border: 1.5px solid rgba(245, 158, 11, 0.4);
    border-radius: 18px;
    padding: 50px 56px;
    box-shadow:
        0 18px 50px rgba(10, 34, 64, 0.09),
        0 0 0 10px rgba(235, 244, 252, 0.8);
    position: relative;
}

.parchment-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1.5px solid rgba(245, 158, 11, 0.35);
    padding-bottom: 22px;
    margin-bottom: 30px;
    gap: 16px;
}

.parchment-brand-mark {
    display: flex;
    align-items: center;
    gap: 14px;
}

.letter-logo-mini {
    width: 48px;
    height: 48px;
    object-fit: contain;
}

.letter-title-group {
    display: flex;
    flex-direction: column;
}

.letter-title-main {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--brown-dark);
    line-height: 1.15;
    letter-spacing: 0.04em;
}

.letter-title-sub {
    font-size: 0.8125rem;
    letter-spacing: 0.1em;
    color: var(--gold-dark);
    font-weight: 600;
    text-transform: uppercase;
}

.parchment-seal-stamp {
    width: 64px;
    height: 64px;
    border: 2px solid #C0392B;
    background: rgba(192, 57, 43, 0.06);
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: #C0392B;
    text-align: center;
    font-weight: 800;
    line-height: 1.1;
    box-shadow: inset 0 0 0 1.5px rgba(192, 57, 43, 0.35);
    transform: rotate(-5deg);
    flex-shrink: 0;
}

.parchment-seal-stamp span {
    font-size: 0.65rem;
    letter-spacing: 0.08em;
}

.parchment-seal-stamp small {
    font-size: 0.42rem;
    letter-spacing: 0.04em;
}

/* Letter Content Styling */
.parchment-content {
    font-family: 'Lora', serif;
    font-size: 1.05rem;
    color: #2D3748;
    line-height: 1.85;
}

.parchment-intro-card {
    margin-bottom: 34px;
    padding-bottom: 24px;
    border-bottom: 1px dashed rgba(245, 158, 11, 0.3);
}

.parchment-salutation {
    font-size: 1.35rem;
    font-weight: 700;
    color: var(--primary-dark);
    margin-bottom: 12px;
    font-family: var(--font-heading);
}

.parchment-lead-para {
    font-size: 1.1rem;
    font-style: italic;
    color: var(--brown);
    margin-bottom: 18px;
}

.letter-profound-quote {
    background: rgba(22, 143, 232, 0.06);
    border-left: 4px solid var(--primary-blue);
    padding: 16px 22px;
    border-radius: 0 10px 10px 0;
    font-size: 1.05rem;
    line-height: 1.75;
    color: var(--brown-dark);
}

/* Letter 7 Sections */
.letter-sections-list {
    display: flex;
    flex-direction: column;
    gap: 32px;
}

.letter-section-item {
    background: #FFFFFF;
    border: 1px solid rgba(22, 143, 232, 0.16);
    border-radius: var(--radius-md);
    padding: 26px 28px;
    box-shadow: 0 4px 16px rgba(10, 34, 64, 0.04);
    transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.letter-section-item:hover {
    box-shadow: 0 8px 24px rgba(10, 34, 64, 0.08);
}

.letter-item-header {
    display: flex;
    align-items: center;
    gap: 14px;
    margin-bottom: 16px;
    border-bottom: 1px solid rgba(245, 158, 11, 0.2);
    padding-bottom: 10px;
}

.letter-item-num {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--gold-light) 0%, var(--gold) 100%);
    color: #0A2240;
    font-weight: 800;
    font-size: 0.875rem;
    flex-shrink: 0;
}

.letter-item-title {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--brown-dark);
    margin: 0;
    line-height: 1.3;
}

.letter-item-body {
    display: flex;
    flex-direction: column;
    gap: 14px;
    font-size: 1rem;
    line-height: 1.8;
}

.letter-quote-callout {
    font-style: italic;
    background: #FDF9EE;
    border-left: 3px solid var(--gold);
    padding: 12px 18px;
    border-radius: 0 8px 8px 0;
    color: var(--brown-dark);
    font-weight: 500;
}

.letter-key-principle {
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--primary-dark);
    background: rgba(22, 143, 232, 0.07);
    padding: 10px 16px;
    border-radius: 8px;
    border: 1px dashed rgba(22, 143, 232, 0.3);
}

.letter-key-principle.highlight-gold {
    background: rgba(245, 158, 11, 0.1);
    color: #9A5B00;
    border-color: rgba(245, 158, 11, 0.4);
}

.letter-key-principle.highlight-coral {
    background: rgba(255, 112, 67, 0.09);
    color: #C0392B;
    border-color: rgba(255, 112, 67, 0.35);
}

/* Generation Grid (Section 2) */
.letter-generations-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
    margin: 6px 0;
}

.letter-gen-box {
    background: var(--body-bg);
    border: 1px solid rgba(22, 143, 232, 0.2);
    border-radius: 10px;
    padding: 16px 14px;
    text-align: center;
}

.lgb-badge {
    display: inline-block;
    background: var(--primary-blue);
    color: #FFFFFF;
    font-weight: 700;
    font-size: 0.75rem;
    letter-spacing: 0.08em;
    padding: 4px 10px;
    border-radius: var(--radius-pill);
    margin-bottom: 10px;
}

.letter-gen-box p {
    font-size: 0.875rem;
    line-height: 1.55;
    color: var(--text);
    margin: 0;
}

/* Three Pillars (Section 4) */
.letter-three-pillars {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 14px;
    margin: 8px 0;
}

.pillar-card {
    background: var(--body-bg);
    border: 1px solid rgba(245, 158, 11, 0.3);
    border-radius: 10px;
    padding: 16px 12px;
    text-align: center;
}

.pillar-icon {
    font-size: 1.5rem;
    display: block;
    margin-bottom: 6px;
}

.pillar-card strong {
    display: block;
    font-size: 0.9rem;
    color: var(--brown-dark);
    margin-bottom: 4px;
}

.pillar-card p {
    font-size: 0.8125rem;
    color: var(--text-muted);
    line-height: 1.4;
    margin: 0;
}

/* Guidance & Two Anchors (Section 5) */
.letter-bullet-guidance {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 10px;
    padding-left: 0;
}

.letter-bullet-guidance li {
    position: relative;
    padding-left: 24px;
    font-size: 0.95rem;
}

.letter-bullet-guidance li::before {
    content: "✦";
    position: absolute;
    left: 0;
    top: 0;
    color: var(--primary-blue);
    font-size: 0.85rem;
}

.letter-two-anchors {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin-top: 6px;
}

.anchor-badge {
    background: #F3F8FD;
    border: 1px solid rgba(22, 143, 232, 0.25);
    border-radius: 10px;
    padding: 14px;
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 0.875rem;
    color: var(--brown-dark);
}

.anchor-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
}

/* Actions Checklist (Section 6) */
.letter-actions-checklist {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin: 6px 0;
}

.action-item-pill {
    background: #FDF9EE;
    border: 1px solid rgba(245, 158, 11, 0.35);
    border-radius: 8px;
    padding: 10px 14px;
    font-size: 0.92rem;
    font-weight: 600;
    color: var(--brown-dark);
    display: flex;
    align-items: center;
    gap: 10px;
}

/* Family Signature Table (Section 7) */
.letter-signatures-table {
    margin-top: 20px;
    border: 1.5px solid rgba(245, 158, 11, 0.4);
    border-radius: 12px;
    background: #FFFCF7;
    overflow: hidden;
    text-align: center;
}

.sig-header-title {
    background: rgba(245, 158, 11, 0.15);
    color: var(--brown-dark);
    font-weight: 700;
    font-size: 0.875rem;
    letter-spacing: 0.1em;
    padding: 10px;
    border-bottom: 1px solid rgba(245, 158, 11, 0.3);
}

.sig-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    divide-x: 1px solid rgba(245, 158, 11, 0.25);
}

.sig-cell {
    padding: 24px 10px 18px;
    display: flex;
    flex-direction: column;
    align-items: center;
    border-right: 1px solid rgba(245, 158, 11, 0.25);
}

.sig-cell:last-child {
    border-right: none;
}

.sig-role {
    font-weight: 800;
    font-size: 1.1rem;
    color: var(--primary-dark);
    margin-bottom: 6px;
    font-family: var(--font-heading);
}

.sig-sub {
    font-size: 0.72rem;
    font-style: italic;
    color: var(--text-light);
}

.sig-footer-note {
    background: rgba(22, 143, 232, 0.06);
    font-size: 0.8125rem;
    font-style: italic;
    color: var(--primary-dark);
    padding: 8px;
    border-top: 1px dashed rgba(245, 158, 11, 0.3);
}

/* ============================================================
   REALISTIC HERITAGE ENVELOPE (GIAO DIỆN PHONG THƯ CỘI NGUỒN)
   ============================================================ */
.heritage-envelope-wrapper {
    max-width: 720px;
    margin: 30px auto 10px;
    perspective: 1200px;
}

.heritage-envelope-card {
    display: block;
    text-decoration: none;
    background: linear-gradient(145deg, #FFFDF8 0%, #F5ECDA 100%);
    border: 2px solid rgba(212, 163, 89, 0.65);
    border-radius: 20px;
    padding: 50px 36px 44px;
    box-shadow: 0 16px 45px rgba(10, 34, 64, 0.1), 0 0 0 1px rgba(255, 255, 255, 0.7) inset;
    position: relative;
    overflow: hidden;
    cursor: pointer;
    transition: all 0.4s cubic-bezier(0.2, 0.8, 0.2, 1);
    text-align: center;
}

.heritage-envelope-card:hover {
    transform: translateY(-8px) scale(1.015);
    box-shadow: 0 24px 60px rgba(22, 143, 232, 0.2), 0 0 35px rgba(245, 158, 11, 0.25);
    border-color: var(--gold);
}

/* Diagonal fold lines for realistic envelope look */
.envelope-lines-bg {
    position: absolute;
    inset: 0;
    pointer-events: none;
    opacity: 0.35;
    background: 
        linear-gradient(to bottom right, transparent 49.5%, rgba(190, 140, 70, 0.25) 50%, transparent 50.5%),
        linear-gradient(to bottom left, transparent 49.5%, rgba(190, 140, 70, 0.25) 50%, transparent 50.5%);
}

.envelope-header-tag {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: rgba(22, 143, 232, 0.08);
    border: 1px solid rgba(22, 143, 232, 0.25);
    color: var(--primary-blue);
    padding: 6px 18px;
    border-radius: var(--radius-pill);
    font-size: 0.85rem;
    font-weight: 700;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    margin-bottom: 20px;
    position: relative;
    z-index: 2;
}

.envelope-main-title {
    font-family: var(--font-heading);
    font-size: 1.85rem;
    font-weight: 800;
    color: var(--primary-dark);
    margin: 0 0 10px;
    line-height: 1.3;
    position: relative;
    z-index: 2;
}

.envelope-sub-recipient {
    font-family: 'Lora', serif;
    font-size: 1.15rem;
    font-style: italic;
    color: var(--brown);
    margin: 0 0 28px;
    position: relative;
    z-index: 2;
}

/* Wax Seal Stamp in the Center */
.wax-seal-container {
    margin: 0 auto 26px;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
    z-index: 2;
}

.wax-seal-stamp {
    width: 105px;
    height: 105px;
    border-radius: 50%;
    background: radial-gradient(circle at 35% 35%, #EF4444 0%, #B91C1C 65%, #7F1D1D 100%);
    border: 3px solid #FCD34D;
    box-shadow: 0 8px 25px rgba(185, 28, 28, 0.4), inset 0 2px 5px rgba(255, 255, 255, 0.4);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: #FFFBEB;
    transition: transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1), box-shadow 0.3s ease;
}

.heritage-envelope-card:hover .wax-seal-stamp {
    transform: scale(1.12) rotate(6deg);
    box-shadow: 0 12px 32px rgba(185, 28, 28, 0.55), 0 0 25px rgba(252, 211, 77, 0.6);
}

.wax-seal-icon {
    font-size: 1.8rem;
    line-height: 1;
    margin-bottom: 2px;
}

.wax-seal-text {
    font-size: 0.65rem;
    font-weight: 800;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

/* Main CTA Button inside the Envelope */
.envelope-open-action {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    background: linear-gradient(135deg, var(--red) 0%, #B91C1C 100%);
    color: #FFFFFF !important;
    padding: 16px 38px;
    border-radius: var(--radius-pill);
    font-family: var(--font-heading);
    font-size: 1.15rem;
    font-weight: 800;
    letter-spacing: 0.03em;
    box-shadow: 0 8px 25px rgba(220, 38, 38, 0.35);
    border: 2px solid rgba(255, 255, 255, 0.25);
    transition: all 0.3s ease;
    position: relative;
    z-index: 2;
}

.heritage-envelope-card:hover .envelope-open-action {
    background: linear-gradient(135deg, #EF4444 0%, #DC2626 100%);
    box-shadow: 0 12px 35px rgba(220, 38, 38, 0.55);
    transform: translateY(-2px);
}

.envelope-hint-footer {
    margin-top: 16px;
    font-size: 0.88rem;
    color: var(--text-light);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    position: relative;
    z-index: 2;
}

/* Letter Toggle Controls */
.letter-toggle-control {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 14px;
    margin-top: 28px;
}

.parchment-footer-cta {
    margin-top: 36px;
    text-align: center;
}

/* Audio Player Interactive enhancements */
.memory-card-voice {
    cursor: pointer;
    transition: transform 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
}

.memory-card-voice:hover {
    transform: translateY(-4px);
    border-color: var(--gold);
    box-shadow: 0 10px 24px rgba(152, 43, 43, 0.15);
}

.voice-click-hint {
    display: inline-block;
    margin-top: 12px;
    font-size: 0.78rem;
    font-weight: 700;
    color: var(--red);
    background: rgba(152, 43, 43, 0.08);
    padding: 4px 12px;
    border-radius: 20px;
    animation: gentleFloat 2.5s infinite ease-in-out;
}

.voice-story-player {
    cursor: pointer;
    transition: background 0.3s ease, border-color 0.3s ease;
}

.voice-story-player:hover {
    background: #FDF4E5;
    border-color: var(--gold);
}

/* Active Audio Playing Waveform */
.memory-card-voice.is-playing .v-bar,
.voice-story-player.is-playing .waveform-bar {
    animation: soundWave 0.6s infinite alternate ease-in-out;
}

.memory-card-voice.is-playing .v-bar:nth-child(1) {
    animation-delay: 0.1s;
}

.memory-card-voice.is-playing .v-bar:nth-child(2) {
    animation-delay: 0.25s;
}

.memory-card-voice.is-playing .v-bar:nth-child(3) {
    animation-delay: 0.15s;
}

.memory-card-voice.is-playing .v-bar:nth-child(4) {
    animation-delay: 0.3s;
}

.memory-card-voice.is-playing .v-bar:nth-child(5) {
    animation-delay: 0.05s;
}

@keyframes soundWave {
    0% {
        height: 6px;
    }

    100% {
        height: 28px;
    }
}

/* ------------------------------------------------------------
   Interactive Creator Section (Bản mẫu Cẩm Nang)
   ------------------------------------------------------------ */
.interactive-creator-section {
    background: linear-gradient(180deg, #EDF5FC 0%, #E2F0FB 100%);
    border-top: 1px solid rgba(56, 189, 248, 0.22);
    border-bottom: 1px solid rgba(56, 189, 248, 0.22);
    position: relative;
    overflow: hidden;
}

.creator-interactive-box {
    display: grid;
    grid-template-columns: 1.1fr 0.9fr;
    gap: 40px;
    align-items: center;
    background: var(--white);
    border-radius: 20px;
    padding: 40px;
    box-shadow: 0 16px 40px rgba(10, 34, 64, 0.08);
    border: 1px solid rgba(56, 189, 248, 0.25);
}

.creator-form-side {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.creator-input-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
    text-align: left;
}

.creator-label {
    font-weight: 700;
    font-size: 0.95rem;
    color: var(--brown-dark);
}

.creator-input,
.creator-select {
    width: 100%;
    padding: 12px 16px;
    border-radius: 10px;
    border: 1.5px solid rgba(56, 189, 248, 0.3);
    background: #F2F7FC;
    font-family: inherit;
    font-size: 0.95rem;
    color: var(--brown-dark);
    outline: none;
    transition: border-color 0.3s ease, background 0.3s ease;
}

.creator-input:focus,
.creator-select:focus {
    border-color: var(--red);
    background: var(--white);
    box-shadow: 0 0 0 3px rgba(22, 143, 232, 0.15);
}

.generation-selector {
    display: flex;
    gap: 10px;
}

.gen-btn {
    flex: 1;
    padding: 10px;
    border: 1.5px solid rgba(56, 189, 248, 0.3);
    background: var(--paper-bg);
    border-radius: 8px;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--brown-dark);
    cursor: pointer;
    transition: all 0.25s ease;
}

.gen-btn.active,
.gen-btn:hover {
    background: var(--red);
    color: var(--white);
    border-color: var(--red);
}

.creator-cta-row {
    margin-top: 10px;
}

.btn-creator-cta {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    width: 100%;
    padding: 14px 24px;
    font-size: 1.05rem;
}

/* 3D Live Book Preview */
.creator-preview-side {
    display: flex;
    justify-content: center;
    align-items: center;
    perspective: 1000px;
}

.preview-book-wrap {
    width: 100%;
    max-width: 320px;
    transform: rotateY(-8deg) rotateX(4deg);
    transition: transform 0.5s cubic-bezier(0.25, 1, 0.5, 1);
}

.preview-book-wrap:hover {
    transform: rotateY(0deg) rotateX(0deg) scale(1.03);
}

.live-book-cover {
    background: linear-gradient(135deg, #072244 0%, #0E487E 60%, #1770BE 100%);
    border-radius: 12px 18px 18px 12px;
    padding: 24px 20px;
    box-shadow:
        -8px 8px 24px rgba(7, 34, 68, 0.35),
        -2px 2px 6px rgba(0, 0, 0, 0.2),
        inset -4px 0 10px rgba(0, 0, 0, 0.4);
    position: relative;
    border-left: 10px solid #04162E;
}

.live-book-frame {
    border: 1.5px solid rgba(245, 158, 11, 0.7);
    border-radius: 8px;
    padding: 28px 16px 20px;
    text-align: center;
    background: radial-gradient(circle at center, rgba(245, 158, 11, 0.12) 0%, transparent 70%);
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 380px;
    box-shadow: inset 0 0 0 1px rgba(56, 189, 248, 0.25);
}

.live-book-top-badge {
    font-size: 0.7rem;
    letter-spacing: 0.2em;
    font-weight: 700;
    color: var(--gold-light);
    margin-bottom: 24px;
}

.live-book-family-title {
    font-family: var(--font-heading);
    font-size: 1.45rem;
    font-weight: 800;
    color: #FFE6A8;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    line-height: 1.25;
    margin-bottom: 12px;
    text-shadow: 0 2px 8px rgba(0, 0, 0, 0.6);
    transition: all 0.3s ease;
}

.live-book-ornament {
    color: var(--gold);
    font-size: 0.85rem;
    letter-spacing: 0.4em;
    margin-bottom: 18px;
}

.live-book-motto {
    font-family: 'Lora', serif;
    font-size: 0.95rem;
    font-style: italic;
    color: #E0F2FE;
    line-height: 1.55;
    margin-bottom: auto;
    padding: 0 4px;
    transition: all 0.3s ease;
}

.live-book-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    margin-top: 24px;
    padding-top: 14px;
    border-top: 1px dashed rgba(245, 158, 11, 0.35);
}

.live-book-gen-tag {
    font-size: 0.75rem;
    color: var(--gold-light);
    font-weight: 600;
}

/* Floating Ambient Audio Widget */
.ambient-audio-widget {
    position: fixed;
    bottom: 28px;
    left: 28px;
    z-index: 990;
}

.btn-ambient-toggle {
    background: rgba(255, 255, 255, 0.92);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1.5px solid var(--gold);
    color: var(--brown-dark);
    padding: 8px 18px 8px 10px;
    border-radius: 30px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 10px;
    box-shadow: 0 8px 24px rgba(74, 48, 40, 0.15);
    font-weight: 600;
    font-size: 0.85rem;
    transition: all 0.3s ease;
}

.btn-ambient-toggle:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 28px rgba(152, 43, 43, 0.22);
    border-color: var(--red);
}

.ambient-disc {
    font-size: 1.1rem;
    display: inline-block;
    transition: transform 0.4s ease;
}

.ambient-audio-widget.is-playing .ambient-disc {
    animation: spin 4s linear infinite;
}

.ambient-equalizer {
    display: flex;
    align-items: flex-end;
    gap: 2.5px;
    height: 14px;
}

.ambient-equalizer span {
    width: 2.5px;
    height: 4px;
    background: var(--red);
    border-radius: 1px;
    transition: height 0.2s ease;
}

.ambient-audio-widget.is-playing .ambient-equalizer span:nth-child(1) {
    animation: eqBar 0.6s infinite alternate;
}

.ambient-audio-widget.is-playing .ambient-equalizer span:nth-child(2) {
    animation: eqBar 0.8s infinite alternate 0.2s;
}

.ambient-audio-widget.is-playing .ambient-equalizer span:nth-child(3) {
    animation: eqBar 0.5s infinite alternate 0.4s;
}

@keyframes eqBar {
    0% {
        height: 3px;
    }

    100% {
        height: 14px;
    }
}

@media (prefers-reduced-motion: reduce) {

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }

    .reveal {
        opacity: 1 !important;
        transform: none !important;
    }

    .floating-sub-card,
    .mobile-floating-cta {
        animation: none !important;
    }
}

/* ------------------------------------------------------------
   19. RESPONSIVE BREAKPOINTS
   ------------------------------------------------------------ */
@media (max-width: 1200px) {
    :root {
        --container-pad: 24px;
        --section-pad-y: 90px;
    }

    .hero-grid {
        gap: 40px;
    }
}

@media (max-width: 1024px) {
    .desktop-nav {
        display: none;
    }

    .hamburger-btn {
        display: flex;
    }

    .header-actions {
        gap: 12px;
    }

    #header-cta-btn {
        padding: 8px 18px;
        font-size: 0.875rem;
    }

    .hero-content {
        align-items: center;
        text-align: center;
    }

    .hero-eyebrow::after {
        display: none;
    }

    .living-book-grid {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .living-book-narrative {
        order: -1;
    }

    .journey-showcase-container {
        grid-template-columns: 320px 1fr;
        gap: 24px;
    }

    .final-grid-layout {
        grid-template-columns: 1fr;
        gap: 50px;
    }

    .footer-top-grid {
        grid-template-columns: 1fr 1fr;
    }

    .footer-brand-col {
        grid-column: 1 / -1;
    }

    /* Chapter 6 Rewards Tablet (992px) */
    .hieu-hoc-pillars-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 20px;
    }

    .flow-steps-track {
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        gap: 20px;
    }

    .flow-step-connector {
        display: none;
    }

    .coauthors-grid,
    .ecosystem-grid,
    .corp-models-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 18px;
    }

    .school-principles-grid,
    .point-sources-grid,
    .cooperate-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 16px;
    }
}

/* ============================================================
   ENHANCED STYLES FROM BỘ SƯỜN SLIDE
   ============================================================ */

/* 1. Memory Callout Banner (Chương 2) */
.memory-callout-banner {
    margin-top: 48px;
    background: linear-gradient(135deg, rgba(22, 143, 232, 0.08) 0%, rgba(245, 158, 11, 0.12) 100%);
    border: 1.5px solid rgba(245, 158, 11, 0.35);
    border-radius: var(--radius-md);
    padding: 24px 32px;
    display: flex;
    align-items: center;
    gap: 20px;
    box-shadow: 0 10px 30px rgba(10, 34, 64, 0.04);
}

.callout-sparkle-icon {
    font-size: 2rem;
    flex-shrink: 0;
}

.callout-quote-text {
    font-family: var(--font-serif-accent);
    font-size: 1.2rem;
    color: var(--brown-dark);
    line-height: 1.6;
    font-style: italic;
}

.callout-quote-text strong {
    color: var(--azure);
    font-style: normal;
}

/* 2. Co-authors Grid (Chương 3 - Slide 04: Ai cùng viết cuốn sách này) */
.sub-block-wrapper {
    margin-top: 64px;
    padding-top: 48px;
    border-top: 1px dashed rgba(56, 189, 248, 0.35);
}

.sub-block-header {
    text-align: center;
    max-width: 800px;
    margin: 0 auto 36px;
}

.sub-block-title {
    font-size: 1.75rem;
    color: var(--brown-dark);
    margin-bottom: 12px;
}

.sub-block-desc {
    font-size: 0.975rem;
    color: var(--text-muted);
    line-height: 1.65;
}

.coauthors-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}

.coauthor-card {
    background: #FFFFFF;
    border: 1.5px solid rgba(56, 189, 248, 0.22);
    border-radius: var(--radius-md);
    padding: 24px 20px;
    box-shadow: 0 8px 24px rgba(10, 34, 64, 0.04);
    transition: var(--transition-smooth);
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.coauthor-card:hover {
    transform: translateY(-4px);
    border-color: var(--primary-blue);
    box-shadow: 0 16px 36px rgba(22, 143, 232, 0.12);
}

.coauthor-avatar-img {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    object-fit: cover;
    border: 2.5px solid var(--azure);
    box-shadow: 0 4px 12px rgba(22, 143, 232, 0.2);
    margin-bottom: 2px;
}

.coauthor-name {
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--brown-dark);
}

.coauthor-role-desc {
    font-size: 0.885rem;
    color: var(--text-muted);
    line-height: 1.55;
}

/* 3. Ecosystem 6-Group Grid (Chương 3 - Slide 05: Hệ sinh thái 6 nhóm tính năng) */
.ecosystem-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 22px;
}

.ecosystem-card {
    background: #FFFFFF;
    border: 1.5px solid rgba(56, 189, 248, 0.22);
    border-radius: var(--radius-md);
    padding: 24px;
    box-shadow: 0 8px 24px rgba(10, 34, 64, 0.04);
    transition: var(--transition-smooth);
    display: flex;
    flex-direction: column;
    gap: 12px;
    position: relative;
    overflow: hidden;
}

.ecosystem-card::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--azure), var(--gold));
    opacity: 0;
    transition: var(--transition-smooth);
}

.ecosystem-card:hover {
    transform: translateY(-4px);
    border-color: var(--azure);
    box-shadow: 0 16px 36px rgba(22, 143, 232, 0.12);
}

.ecosystem-card:hover::before {
    opacity: 1;
}

.ecosystem-card.highlight-hieu-hoc {
    border-color: rgba(245, 158, 11, 0.45);
    background: linear-gradient(180deg, #FFFFFF 0%, #FFFDF7 100%);
    box-shadow: 0 10px 30px rgba(245, 158, 11, 0.08);
}

.ecosystem-card.highlight-hieu-hoc::before {
    opacity: 1;
    background: linear-gradient(90deg, #F59E0B, #FF7043);
}

.ecosystem-badge-tag {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    color: var(--azure);
    background: var(--cream);
    padding: 4px 10px;
    border-radius: var(--radius-pill);
    width: fit-content;
}

.highlight-hieu-hoc .ecosystem-badge-tag {
    color: #D97706;
    background: rgba(245, 158, 11, 0.14);
}

.ecosystem-title {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--brown-dark);
}

.ecosystem-feature-list {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.ecosystem-feature-list li {
    font-size: 0.865rem;
    color: var(--text-muted);
    line-height: 1.5;
    display: flex;
    align-items: flex-start;
    gap: 8px;
}

.ecosystem-feature-list li::before {
    content: "✦";
    color: var(--azure);
    font-size: 0.75rem;
    line-height: 1.7;
    flex-shrink: 0;
}

.highlight-hieu-hoc .ecosystem-feature-list li::before {
    color: var(--gold-dark);
}

/* 4. School Principles (Chương 5 - Slide 25: 5 Nguyên tắc trường học) */
.school-principles-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 16px;
    margin-top: 24px;
}

.school-principle-card {
    background: #FFFFFF;
    border: 1.5px solid rgba(56, 189, 248, 0.22);
    border-radius: var(--radius-md);
    padding: 20px 16px;
    text-align: center;
    box-shadow: 0 6px 20px rgba(10, 34, 64, 0.03);
    transition: var(--transition-smooth);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.school-principle-card:hover {
    transform: translateY(-3px);
    border-color: var(--azure);
    box-shadow: 0 12px 28px rgba(22, 143, 232, 0.1);
}

.school-p-icon {
    font-size: 1.6rem;
    margin-bottom: 2px;
}

.school-p-title {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--brown-dark);
    line-height: 1.35;
}

.school-p-desc {
    font-size: 0.8125rem;
    color: var(--text-muted);
    line-height: 1.5;
}

/* 5. Corporate Solutions (Chương 5 - Slide 27-31: 3 Mô hình Doanh nghiệp) */
.corp-models-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 22px;
    margin-top: 24px;
}

.corp-model-card {
    background: #FFFFFF;
    border: 1.5px solid rgba(56, 189, 248, 0.22);
    border-radius: var(--radius-md);
    padding: 28px 22px;
    box-shadow: 0 8px 24px rgba(10, 34, 64, 0.04);
    transition: var(--transition-smooth);
    display: flex;
    flex-direction: column;
    gap: 14px;
}

.corp-model-card:hover {
    transform: translateY(-4px);
    border-color: var(--primary-blue);
    box-shadow: 0 16px 36px rgba(22, 143, 232, 0.12);
}

.corp-model-num {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--azure);
}

.corp-model-title {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--brown-dark);
    line-height: 1.35;
}

.corp-model-desc {
    font-size: 0.885rem;
    color: var(--text-muted);
    line-height: 1.55;
}

.corp-model-features {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    flex-direction: column;
    gap: 8px;
    border-top: 1px dashed rgba(56, 189, 248, 0.25);
    padding-top: 14px;
}

.corp-model-features li {
    font-size: 0.84rem;
    color: var(--text);
    display: flex;
    align-items: flex-start;
    gap: 8px;
    line-height: 1.45;
}

.corp-model-features li span {
    color: var(--azure);
    font-weight: bold;
}

/* 6. Point Sources & Ecosystem Loop (Chương 6 - Slide 16, 17, 21) */
.point-sources-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 18px;
    margin-top: 24px;
}

.point-source-card {
    background: #FFFFFF;
    border: 1.5px solid rgba(56, 189, 248, 0.22);
    border-radius: var(--radius-md);
    padding: 22px 18px;
    box-shadow: 0 6px 20px rgba(10, 34, 64, 0.03);
    transition: var(--transition-smooth);
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.point-source-card:hover {
    transform: translateY(-3px);
    border-color: var(--azure);
    box-shadow: 0 12px 28px rgba(22, 143, 232, 0.1);
}

.point-src-badge {
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--azure);
    background: var(--cream);
    padding: 3px 8px;
    border-radius: var(--radius-pill);
    width: fit-content;
}

.point-src-title {
    font-size: 1.025rem;
    font-weight: 700;
    color: var(--brown-dark);
}

.point-src-desc {
    font-size: 0.835rem;
    color: var(--text-muted);
    line-height: 1.5;
}

.ecosystem-loop-box {
    margin-top: 36px;
    background: linear-gradient(135deg, rgba(22, 143, 232, 0.06) 0%, rgba(245, 158, 11, 0.08) 100%);
    border: 1.5px solid rgba(22, 143, 232, 0.25);
    border-radius: var(--radius-md);
    padding: 28px 32px;
    display: flex;
    align-items: center;
    gap: 24px;
}

.loop-icon-badge {
    font-size: 2.2rem;
    flex-shrink: 0;
}

.loop-content h4 {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--brown-dark);
    margin-bottom: 6px;
}

.loop-content p {
    font-size: 0.925rem;
    color: var(--text-muted);
    line-height: 1.6;
}

/* 7. Cooperation Invitation Grid (Chương Cuối - Slide 33) */
.cooperate-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 16px;
    margin-bottom: 40px;
}

.cooperate-card {
    background: #FFFFFF;
    border: 1.5px solid rgba(56, 189, 248, 0.22);
    border-radius: var(--radius-md);
    padding: 20px 16px;
    text-align: center;
    box-shadow: 0 6px 20px rgba(10, 34, 64, 0.03);
    transition: var(--transition-smooth);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}

.cooperate-card:hover {
    transform: translateY(-3px);
    border-color: var(--azure);
    box-shadow: 0 12px 28px rgba(22, 143, 232, 0.1);
}

.coop-icon {
    font-size: 1.75rem;
}

.coop-title {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--brown-dark);
}

.coop-desc {
    font-size: 0.8rem;
    color: var(--text-muted);
    line-height: 1.45;
}

@media (max-width: 768px) {
    :root {
        --section-pad-y: 60px;
        --container-pad: 20px;
    }

    /* Prevent any horizontal screen overflow */
    body,
    html,
    main,
    section {
        width: 100%;
        max-width: 100vw;
        overflow-x: hidden;
    }

    .container {
        width: 100%;
        max-width: 100%;
        padding-left: var(--container-pad);
        padding-right: var(--container-pad);
        box-sizing: border-box;
    }

    .header-actions {
        gap: 10px;
    }

    #header-cta-btn {
        padding: 7px 14px;
        font-size: 0.8125rem;
        font-weight: 600;
        white-space: nowrap;
    }

    /* Parchment Letter Mobile */
    .parchment-letter-wrapper {
        width: 100%;
        max-width: 100%;
    }

    .parchment-letter-paper {
        padding: 28px 16px;
        border-radius: 14px;
        box-shadow: 0 10px 30px rgba(10, 34, 64, 0.08);
    }

    .parchment-header {
        flex-direction: column;
        text-align: center;
        gap: 14px;
    }

    .parchment-brand-mark {
        flex-direction: column;
        text-align: center;
        gap: 8px;
    }

    .letter-title-main {
        font-size: 1.4rem;
    }

    .letter-title-sub {
        font-size: 0.8125rem;
    }

    .letter-section-item {
        padding: 18px 14px;
        margin-bottom: 16px;
    }

    .letter-item-title {
        font-size: 1.05rem;
    }

    .letter-generations-grid,
    .letter-three-pillars,
    .letter-two-anchors {
        grid-template-columns: 1fr;
        gap: 10px;
    }

    .sig-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
    }

    .sig-cell {
        padding: 14px 8px;
    }

    .btn-letter-toggle {
        width: 100%;
        justify-content: center;
        padding: 12px 16px;
        font-size: 0.875rem;
    }

    /* Chapter 4 Journey Slider Responsive (Mobile/Tablet) */
    .journey-showcase-container {
        margin-top: 24px;
        margin-bottom: 32px;
        width: 100%;
    }

    .journey-slider-viewport {
        border-radius: 16px;
        width: 100%;
    }

    .slider-nav-btn {
        width: 40px;
        height: 40px;
        font-size: 1rem;
    }

    .slider-nav-btn.prev {
        left: 8px;
    }

    .slider-nav-btn.next {
        right: 8px;
    }

    /* Memory Layout to Stack */
    .memory-row-top,
    .memory-row-bottom {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .memory-row-top .memory-card-img-wrap,
    .memory-row-bottom .memory-card-img-wrap {
        height: 220px;
    }

    .memory-card-voice {
        min-height: 160px;
        padding: 20px 16px;
    }

    /* Audience Cards to Stack */
    .audience-cards-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .audience-card {
        height: 340px;
    }

    /* Chapter 6 Rewards Responsive (Mobile <= 768px) */
    .hieu-hoc-pillars-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 16px;
    }

    .hieu-hoc-pillar-card {
        height: 380px;
    }

    .hieu-hoc-flow-box {
        padding: 24px 16px;
        border-radius: 20px;
    }

    .flow-steps-track {
        display: flex;
        flex-direction: column;
        gap: 12px;
        width: 100%;
        align-items: stretch;
    }

    .flow-step-node {
        width: 100%;
        height: 270px;
        flex: none;
    }

    .flow-step-connector {
        display: block;
        transform: rotate(90deg);
        margin: 2px auto;
        font-size: 1.2rem;
        line-height: 1;
        color: var(--primary-blue);
        opacity: 0.6;
        align-self: center;
    }

    /* Text always clear and readable on mobile */
    .pillar-desc-short,
    .node-desc-short {
        max-height: 80px;
        opacity: 1;
        transform: translateY(0);
        margin-top: 4px;
    }

    .reward-lookup-section {
        padding: 24px 16px;
    }

    .reward-tab-nav {
        gap: 8px;
    }

    .reward-tab-btn {
        padding: 10px 16px;
        font-size: 0.875rem;
    }

    /* Smart Mobile Card Transformation for Table (Zero Horizontal Scroll) */
    .reward-table-responsive {
        border: none;
        background: transparent;
        box-shadow: none;
        overflow: visible;
    }

    .reward-data-table {
        display: block;
        width: 100%;
    }

    .reward-data-table thead {
        display: none;
    }

    .reward-data-table tbody {
        display: flex;
        flex-direction: column;
        gap: 12px;
        width: 100%;
    }

    .reward-data-table tbody tr {
        display: grid;
        grid-template-columns: 1fr auto;
        grid-template-areas:
            "title title"
            "cond cond"
            "point vnd";
        align-items: center;
        gap: 8px 12px;
        background: #FFFFFF;
        border: 1.5px solid rgba(56, 189, 248, 0.25);
        border-radius: 16px;
        padding: 16px 18px;
        box-shadow: 0 4px 16px rgba(10, 34, 64, 0.04);
        transition: all 0.25s ease;
    }

    .reward-data-table tbody tr:hover {
        border-color: var(--primary-blue);
        transform: translateY(-2px);
        box-shadow: 0 8px 24px rgba(22, 143, 232, 0.12);
    }

    .reward-data-table td {
        display: block;
        padding: 0;
        border: none;
        width: 100% !important;
    }

    .reward-data-table tbody td:nth-child(1) {
        grid-area: title;
        font-size: 0.975rem;
        font-weight: 700;
        color: var(--brown-dark);
        line-height: 1.4;
    }

    .reward-data-table tbody td:nth-child(2) {
        grid-area: cond;
        font-size: 0.835rem;
        color: var(--text-muted);
        line-height: 1.45;
        padding-bottom: 8px;
        border-bottom: 1px dashed rgba(56, 189, 248, 0.22);
    }

    .reward-data-table tbody td:nth-child(3) {
        grid-area: point;
        display: flex;
        align-items: center;
        justify-self: start;
        width: auto !important;
    }

    .reward-data-table tbody td:nth-child(4) {
        grid-area: vnd;
        display: flex;
        align-items: center;
        justify-self: end;
        text-align: right;
        width: auto !important;
    }

    .reward-data-table tbody td:nth-child(4)::before {
        content: "⇌ ";
        color: var(--text-light);
        margin-right: 4px;
        font-size: 0.85rem;
        font-weight: normal;
    }

    .reward-grid-showcase {
        grid-template-columns: 1fr;
        gap: 24px;
        margin-top: 24px;
        margin-bottom: 24px;
    }

    .reward-showcase-card {
        padding: 24px 20px;
    }

    .reward-img-frame {
        height: 220px;
    }

    .reward-privacy-note {
        flex-direction: column;
        text-align: center;
        gap: 6px;
        padding: 12px 14px;
    }

    .btn-reward-main {
        width: 100%;
        justify-content: center;
        padding: 12px 20px;
        font-size: 0.95rem;
    }

    .footer-top-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .footer-bottom-bar {
        flex-direction: column;
        gap: 12px;
        text-align: center;
    }

    /* Enhanced Slide Framework Components Mobile Overrides */
    .memory-callout-banner {
        flex-direction: column;
        text-align: center;
        padding: 20px 16px;
        gap: 12px;
    }

    .callout-quote-text {
        font-size: 1.05rem;
    }

    .sub-block-wrapper {
        margin-top: 40px;
        padding-top: 32px;
    }

    .sub-block-title {
        font-size: 1.45rem;
    }

    .coauthors-grid,
    .ecosystem-grid,
    .corp-models-grid {
        grid-template-columns: 1fr;
        gap: 14px;
    }

    .school-principles-grid,
    .point-sources-grid,
    .cooperate-grid {
        grid-template-columns: 1fr;
        gap: 12px;
    }

    .ecosystem-loop-box {
        flex-direction: column;
        text-align: center;
        padding: 20px 16px;
        gap: 12px;
    }

    /* Ambient Audio Widget Mobile */
    .ambient-audio-widget {
        bottom: 16px;
        right: 16px;
    }
}

@media (max-width: 480px) {
    :root {
        --container-pad: 16px;
        --section-pad-y: 50px;
    }

    .header-actions {
        gap: 8px;
    }

    #header-cta-btn {
        padding: 6px 11px;
        font-size: 0.78125rem;
        letter-spacing: -0.01em;
    }

    .hamburger-btn {
        width: 36px;
        height: 36px;
    }

    .logo-symbol {
        width: 40px;
        height: 40px;
    }

    .logo-main-title {
        font-size: 1.5rem;
    }

    .logo-sub-title {
        font-size: 0.6rem;
    }

    .hero-section {
        margin-top: 72px;
        min-height: auto;
        padding-top: 36px;
        padding-bottom: 50px;
        background-color: #0B5FA5;
        background-image:
            linear-gradient(180deg, rgba(8, 48, 88, 0.92) 0%, rgba(10, 68, 122, 0.80) 50%, rgba(8, 48, 88, 0.94) 100%),
            url('../assets/images/trang_bia.png');
        background-position: center center;
    }

    .hero-scroll-indicator {
        display: none;
    }

    .hero-headline {
        font-size: 1.95rem;
        line-height: 1.25;
    }

    .hero-desc {
        font-size: 0.95rem;
    }

    .hero-cta-group {
        flex-direction: column;
        width: 100%;
        gap: 10px;
    }

    .hero-cta-group .btn {
        width: 100%;
    }

    .section-headline {
        font-size: 1.65rem;
    }

    .parchment-letter-paper {
        padding: 22px 12px;
    }

    .sig-grid {
        grid-template-columns: 1fr 1fr;
        gap: 8px;
    }

    .sig-cell {
        padding: 10px 4px;
    }

    .sig-role {
        font-size: 0.75rem;
    }

    .sig-name-sample {
        font-size: 0.72rem;
    }

    .journey-slider-viewport {
        border-radius: 14px;
    }

    .slide-caption-bar {
        padding: 10px 14px;
        gap: 8px;
        font-size: 0.8125rem;
    }

    .caption-step {
        font-size: 0.75rem;
        padding: 2px 7px;
    }

    .caption-text {
        font-size: 0.8125rem;
    }

    .slider-nav-btn {
        width: 36px;
        height: 36px;
        font-size: 0.95rem;
    }

    .hieu-hoc-pillars-grid {
        grid-template-columns: 1fr;
        gap: 14px;
    }

    .hieu-hoc-pillar-card {
        height: 350px;
    }

    .flow-step-node {
        height: 250px;
    }

    .reward-rate-badge {
        font-size: 0.78125rem;
        padding: 6px 14px;
        text-align: center;
    }

    .reward-tab-btn {
        width: 100%;
        justify-content: center;
    }

    .reward-data-table tbody tr {
        padding: 14px;
        gap: 6px;
    }

    .reward-data-table tbody td:nth-child(1) {
        font-size: 0.925rem;
    }

    .reward-data-table tbody td:nth-child(2) {
        font-size: 0.8rem;
    }

    .point-badge {
        font-size: 0.8rem;
        padding: 4px 10px;
    }

    .vnd-val {
        font-size: 0.825rem;
    }

    .reward-card-title {
        font-size: 1.25rem;
    }

    .reward-img-frame {
        height: 190px;
    }

    .couplet-box {
        padding: 18px 14px;
        margin-top: 18px;
    }

    .couplet-line {
        font-size: 1.05rem;
        line-height: 1.55;
    }

    .form-card-container {
        padding: 24px 16px;
    }
}

@media (max-width: 360px) {
    :root {
        --container-pad: 12px;
    }

    #header-cta-btn {
        padding: 5px 8px;
        font-size: 0.7rem;
    }

    .hero-headline {
        font-size: 1.75rem;
    }
}