/* ==========================================================================
   B.A. 5TH SEMESTER DIGITAL TEXTBOOK - MODERN ACADEMIC DESIGN SYSTEM
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+Devanagari:wght@300;400;500;600;700;800&family=Poppins:wght@300;400;500;600;700;800&display=swap');

/* --------------------------------------------------------------------------
   1. MODERN COLOR PALETTE & DESIGN TOKENS
   -------------------------------------------------------------------------- */
:root {
    /* Base Theme - Light Mode (Ultra Clean & Frosted) */
    --bg-body: #f8fafc;
    --bg-card: #ffffff;
    --bg-card-alt: #f1f5f9;
    --bg-nav: #0f172a;
    --bg-sidebar: #ffffff;
    --border-color: #e2e8f0;
    --border-strong: #cbd5e1;
    
    --text-main: #0f172a;
    --text-muted: #334155;
    --text-subtle: #64748b;
    --text-on-dark: #ffffff;
    --text-nav: #94a3b8;
    --text-nav-active: #ffffff;

    /* Modern Gradient Overlays */
    --hero-gradient: linear-gradient(135deg, #0f172a 0%, #1e1b4b 50%, #1e293b 100%);
    --card-gradient: linear-gradient(180deg, rgba(255, 255, 255, 1) 0%, rgba(248, 250, 252, 1) 100%);
    --accent-gradient: linear-gradient(135deg, #4f46e5 0%, #3b82f6 100%);

    /* Shadows & Glows */
    --shadow-sm: 0 2px 8px 0 rgba(15, 23, 42, 0.04);
    --shadow-md: 0 8px 24px -4px rgba(15, 23, 42, 0.08);
    --shadow-lg: 0 16px 36px -6px rgba(15, 23, 42, 0.12);
    --shadow-xl: 0 24px 48px -12px rgba(15, 23, 42, 0.18);
    --glow-brand: 0 0 24px rgba(79, 70, 229, 0.3);

    /* Subject Accent Schemes (Vibrant Modern Palette) */
    --accent-color: #4f46e5;
    --accent-hover: #4338ca;
    --accent-light: #e0e7ff;
    --accent-dark: #3730a3;
    --accent-glow: rgba(79, 70, 229, 0.2);

    --eco-accent: #4f46e5;
    --eco-light: #e0e7ff;
    --geo-accent: #10b981;
    --geo-light: #d1fae5;
    --socio-accent: #8b5cf6;
    --socio-light: #ede9fe;
    --vac-accent: #f59e0b;
    --vac-light: #fef3c7;

    /* Functional Colors */
    --success: #10b981;
    --success-bg: #d1fae5;
    --warning: #f59e0b;
    --warning-bg: #fef3c7;
    --danger: #ef4444;
    --danger-bg: #fee2e2;
    --info: #06b6d4;
    --info-bg: #cffaff;

    /* Dimensions & Radii */
    --header-height: 68px;
    --sidebar-width: 310px;
    --max-reading-width: 920px;
    --max-container-width: 1320px;
    --radius-sm: 8px;
    --radius-md: 14px;
    --radius-lg: 20px;
    --radius-full: 9999px;

    /* Typography */
    --base-font-size: 16px;
    --font-family-sans: 'Noto Sans Devanagari', 'Poppins', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

/* Dark Theme Overrides (Sleek Glassmorphic Midnight) */
[data-theme="dark"] {
    --bg-body: #090d16;
    --bg-card: rgba(19, 27, 46, 0.85);
    --bg-card-alt: rgba(28, 39, 62, 0.85);
    --bg-nav: #060a12;
    --bg-sidebar: #0e1626;
    --border-color: #22304a;
    --border-strong: #314366;

    --text-main: #f8fafc;
    --text-muted: #cbd5e1;
    --text-subtle: #94a3b8;

    --card-gradient: linear-gradient(180deg, rgba(19, 27, 46, 0.9) 0%, rgba(15, 23, 42, 0.9) 100%);
    --shadow-sm: 0 2px 8px 0 rgba(0, 0, 0, 0.4);
    --shadow-md: 0 8px 24px -4px rgba(0, 0, 0, 0.5);
    --shadow-lg: 0 16px 36px -6px rgba(0, 0, 0, 0.6);

    --accent-light: rgba(79, 70, 229, 0.25);
    --eco-light: rgba(79, 70, 229, 0.25);
    --geo-light: rgba(16, 185, 129, 0.25);
    --socio-light: rgba(139, 92, 246, 0.25);
    --vac-light: rgba(245, 158, 11, 0.25);

    --success-bg: rgba(16, 185, 129, 0.2);
    --warning-bg: rgba(245, 158, 11, 0.2);
    --danger-bg: rgba(239, 68, 68, 0.2);
    --info-bg: rgba(6, 182, 212, 0.2);
}

/* Subject Specific Accent Bindings */
body[data-subject="economics"] {
    --accent-color: var(--eco-accent);
    --accent-light: var(--eco-light);
}
body[data-subject="geography"] {
    --accent-color: var(--geo-accent);
    --accent-light: var(--geo-light);
}
body[data-subject="sociology"] {
    --accent-color: var(--socio-accent);
    --accent-light: var(--socio-light);
}
body[data-subject="vac"] {
    --accent-color: var(--vac-accent);
    --accent-light: var(--vac-light);
}

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

html {
    scroll-behavior: smooth;
    font-size: var(--base-font-size);
}

body {
    font-family: var(--font-family-sans);
    background-color: var(--bg-body);
    color: var(--text-main);
    line-height: 1.75;
    transition: background-color 0.3s ease, color 0.3s ease;
    overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.3;
    color: var(--text-main);
    margin-bottom: 0.5rem;
    letter-spacing: -0.02em;
}

p {
    margin-bottom: 1rem;
    color: var(--text-muted);
}

a {
    color: var(--accent-color);
    text-decoration: none;
    transition: all 0.2s ease;
}

a:hover {
    color: var(--accent-hover);
}

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

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    outline: none;
    background: none;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}
::-webkit-scrollbar-track {
    background: var(--bg-body);
}
::-webkit-scrollbar-thumb {
    background: var(--border-strong);
    border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
    background: var(--accent-color);
}

/* Top Reading Progress Bar */
#reading-progress-bar {
    position: fixed;
    top: 0;
    left: 0;
    height: 4px;
    background: linear-gradient(90deg, #3b82f6, #10b981, #8b5cf6, #f59e0b);
    z-index: 2000;
    width: 0%;
    transition: width 0.1s linear;
}

/* --------------------------------------------------------------------------
   3. MODERN NAVBAR & BREADCRUMB
   -------------------------------------------------------------------------- */
.top-navbar {
    position: sticky;
    top: 0;
    z-index: 1000;
    background-color: var(--bg-nav);
    color: var(--text-on-dark);
    height: var(--header-height);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 1.75rem;
    box-shadow: var(--shadow-md);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(12px);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--text-on-dark);
    font-weight: 700;
    font-size: 1.1rem;
    text-decoration: none;
}

.nav-brand i {
    font-size: 1.75rem;
    background: linear-gradient(135deg, #38bdf8, #818cf8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-brand-text {
    display: flex;
    flex-direction: column;
}

.nav-brand-text .title {
    font-size: 1.05rem;
    font-weight: 800;
    line-height: 1.2;
}

.nav-brand-text .subtitle {
    font-size: 0.72rem;
    color: var(--text-nav);
    font-weight: 400;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 6px;
    list-style: none;
}

.nav-link {
    color: var(--text-nav);
    padding: 8px 14px;
    border-radius: var(--radius-sm);
    font-size: 0.88rem;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 6px;
    transition: all 0.2s ease;
}

.nav-link:hover, .nav-link.active {
    color: var(--text-nav-active);
    background-color: rgba(255, 255, 255, 0.12);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 10px;
}

.nav-btn {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    color: var(--text-on-dark);
    padding: 7px 14px;
    border-radius: var(--radius-full);
    font-size: 0.82rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 6px;
    transition: all 0.2s ease;
}

.nav-btn:hover {
    background: rgba(255, 255, 255, 0.22);
    border-color: rgba(255, 255, 255, 0.4);
    transform: translateY(-1px);
}

.font-resizer-group {
    display: flex;
    align-items: center;
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-sm);
    padding: 2px;
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.font-btn {
    color: var(--text-on-dark);
    padding: 3px 8px;
    font-size: 0.78rem;
    font-weight: 700;
    border-radius: 4px;
}

.font-btn:hover {
    background: rgba(255, 255, 255, 0.2);
}

.mobile-nav-toggle {
    display: none;
    color: var(--text-on-dark);
    font-size: 1.3rem;
    padding: 6px;
}

.sub-header {
    background-color: var(--bg-card);
    border-bottom: 1px solid var(--border-color);
    padding: 12px 1.75rem;
}

.breadcrumb-container {
    max-width: var(--max-container-width);
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 0.85rem;
}

.breadcrumb-links {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-subtle);
    flex-wrap: wrap;
}

/* --------------------------------------------------------------------------
   4. LAYOUT STRUCTURE
   -------------------------------------------------------------------------- */
.main-wrapper {
    max-width: var(--max-container-width);
    margin: 0 auto;
    padding: 1.75rem;
    display: flex;
    gap: 2rem;
    position: relative;
}

.sidebar-toc {
    width: var(--sidebar-width);
    flex-shrink: 0;
    position: sticky;
    top: calc(var(--header-height) + 1.5rem);
    height: calc(100vh - var(--header-height) - 3rem);
    overflow-y: auto;
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.25rem;
    box-shadow: var(--shadow-sm);
}

.toc-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-bottom: 10px;
    margin-bottom: 12px;
    border-bottom: 2px solid var(--accent-light);
}

.toc-header h3 {
    font-size: 0.92rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--accent-color);
    display: flex;
    align-items: center;
    gap: 8px;
}

.toc-group {
    margin-bottom: 1rem;
}

.toc-group-title {
    font-size: 0.85rem;
    font-weight: 700;
    color: var(--text-main);
    margin-bottom: 6px;
}

.toc-item-list {
    list-style: none;
    padding-left: 12px;
    border-left: 2px solid var(--border-color);
}

.toc-link {
    display: block;
    font-size: 0.82rem;
    color: var(--text-muted);
    padding: 5px 8px;
    border-radius: var(--radius-sm);
    transition: all 0.2s ease;
    line-height: 1.4;
}

.toc-link:hover, .toc-link.active {
    color: var(--accent-color);
    font-weight: 700;
    background-color: var(--accent-light);
}

.content-area {
    flex: 1;
    min-width: 0;
    max-width: var(--max-reading-width);
}

/* --------------------------------------------------------------------------
   5. MODERN CARDS & ACADEMIC COMPONENTS
   -------------------------------------------------------------------------- */
.page-hero {
    background: var(--hero-gradient);
    color: #ffffff;
    border-radius: var(--radius-lg);
    padding: 2.5rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
    border: 1px solid var(--border-strong);
}

.page-hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: rgba(255, 255, 255, 0.15);
    backdrop-filter: blur(8px);
    color: #38bdf8;
    font-weight: 700;
    font-size: 0.75rem;
    padding: 5px 14px;
    border-radius: var(--radius-full);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 14px;
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.page-hero h1 {
    font-size: 2.1rem;
    font-weight: 800;
    color: #ffffff;
    margin-bottom: 12px;
    line-height: 1.2;
}

.page-hero p {
    font-size: 1rem;
    color: #cbd5e1;
    margin-bottom: 1.5rem;
}

.page-hero-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1.25rem;
    padding-top: 1.25rem;
    border-top: 1px solid rgba(255, 255, 255, 0.15);
}

.stat-item {
    display: flex;
    flex-direction: column;
}

.stat-value {
    font-size: 1.15rem;
    font-weight: 800;
    color: #38bdf8;
}

.stat-label {
    font-size: 0.78rem;
    color: #94a3b8;
}

/* Textbook Unit & Topic Cards */
.unit-section {
    margin-bottom: 2.5rem;
    scroll-margin-top: calc(var(--header-height) + 1.5rem);
}

.unit-header {
    border-bottom: 2px solid var(--accent-color);
    padding-bottom: 8px;
    margin-bottom: 1.5rem;
}

.unit-tag {
    font-size: 0.75rem;
    font-weight: 800;
    color: var(--accent-color);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.unit-header h2 {
    font-size: 1.6rem;
    font-weight: 800;
    color: var(--text-main);
}

.topic-card {
    background: var(--card-gradient);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.85rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow-sm);
    transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}

.topic-card:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--border-strong);
    transform: translateY(-2px);
}

.topic-title {
    font-size: 1.25rem;
    font-weight: 800;
    color: var(--text-main);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 10px;
}

.topic-number {
    background: var(--accent-gradient);
    color: #ffffff;
    font-size: 0.8rem;
    font-weight: 800;
    padding: 3px 12px;
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-sm);
}

.definition-box {
    background-color: var(--accent-light);
    border-left: 5px solid var(--accent-color);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    padding: 1.35rem;
    margin: 1.35rem 0;
}

.definition-box h4 {
    font-size: 0.95rem;
    font-weight: 800;
    color: var(--accent-color);
    margin-bottom: 6px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.example-box {
    background-color: var(--info-bg);
    border: 1px solid #a5f3fc;
    border-radius: var(--radius-md);
    padding: 1.35rem;
    margin: 1.35rem 0;
}
[data-theme="dark"] .example-box { border-color: #0891b2; }

.example-box h5 {
    color: #0891b2;
    font-size: 0.92rem;
    font-weight: 800;
    margin-bottom: 6px;
}
[data-theme="dark"] .example-box h5 { color: #22d3ee; }

.table-responsive {
    overflow-x: auto;
    margin: 1.5rem 0;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.textbook-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.88rem;
    text-align: left;
}

.textbook-table th {
    background-color: var(--bg-card-alt);
    color: var(--text-main);
    font-weight: 800;
    padding: 14px 18px;
    border-bottom: 2px solid var(--border-color);
}

.textbook-table td {
    padding: 14px 18px;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-muted);
}

.diagram-container {
    background-color: var(--bg-card-alt);
    border: 1px dashed var(--border-strong);
    border-radius: var(--radius-md);
    padding: 1.75rem;
    margin: 1.5rem 0;
    text-align: center;
}

.flowchart-flex {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 12px;
    margin-top: 1rem;
}

.flow-node {
    background-color: var(--bg-card);
    border: 1.5px solid var(--accent-color);
    color: var(--accent-color);
    font-weight: 700;
    font-size: 0.85rem;
    padding: 10px 18px;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
}

.formula-box {
    background-color: var(--bg-card-alt);
    border-left: 5px solid var(--warning);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    padding: 1.35rem;
    margin: 1.35rem 0;
    font-family: monospace;
    font-size: 0.95rem;
}

.formula-title {
    font-family: var(--font-family-sans);
    font-weight: 800;
    color: var(--warning);
    margin-bottom: 6px;
}

.qa-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1.35rem;
    margin-bottom: 1rem;
}

.qa-badge {
    background-color: var(--accent-light);
    color: var(--accent-color);
    font-size: 0.75rem;
    font-weight: 800;
    padding: 3px 10px;
    border-radius: 4px;
}

.flashcard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 1.25rem;
    margin: 1.5rem 0;
}

.flashcard {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1.75rem;
    min-height: 150px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    transition: transform 0.25s ease, box-shadow 0.25s ease;
    user-select: none;
}

.flashcard:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--accent-color);
}

.flashcard .front {
    font-weight: 700;
    font-size: 0.95rem;
    color: var(--accent-color);
}

.flashcard .back {
    display: none;
    font-size: 0.9rem;
    color: var(--text-main);
}

.flashcard.flipped {
    background-color: var(--accent-light);
}
.flashcard.flipped .front { display: none; }
.flashcard.flipped .back { display: block; }

.mcq-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1.35rem;
    margin-bottom: 1rem;
    box-shadow: var(--shadow-sm);
}

.mcq-option {
    padding: 11px 16px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    cursor: pointer;
    background-color: var(--bg-body);
    transition: all 0.2s ease;
}

.mcq-option:hover {
    border-color: var(--accent-color);
    background-color: var(--accent-light);
}

.mcq-option.correct {
    background-color: var(--success-bg);
    border-color: var(--success);
    color: var(--success);
    font-weight: 700;
}

.mcq-option.wrong {
    background-color: var(--danger-bg);
    border-color: var(--danger);
    color: var(--danger);
}

.mcq-explanation {
    margin-top: 10px;
    padding: 12px 16px;
    background-color: var(--bg-card-alt);
    border-left: 4px solid var(--accent-color);
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    color: var(--text-muted);
    display: none;
}

.glossary-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1rem;
    margin: 1.5rem 0;
}

.glossary-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1.15rem;
}

.glossary-term {
    font-weight: 800;
    color: var(--accent-color);
    font-size: 0.92rem;
    margin-bottom: 4px;
}

/* --------------------------------------------------------------------------
   6. OFFICIAL SYLLABUS LIGHTBOX / MODAL VIEWER
   -------------------------------------------------------------------------- */
.syllabus-modal-overlay {
    position: fixed;
    inset: 0;
    background-color: rgba(2, 6, 23, 0.88);
    backdrop-filter: blur(8px);
    z-index: 3500;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.25s ease, visibility 0.25s ease;
    padding: 0.75rem;
}

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

.syllabus-modal-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-strong);
    border-radius: var(--radius-lg);
    width: 100%;
    max-width: 1100px;
    height: 92vh;
    display: flex;
    flex-direction: column;
    box-shadow: var(--shadow-xl);
    overflow: hidden;
}

.syllabus-modal-header {
    background-color: var(--bg-nav);
    color: var(--text-on-dark);
    padding: 12px 18px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    flex-wrap: wrap;
    border-bottom: 1px solid rgba(255, 255, 255, 0.12);
}

.syllabus-modal-title {
    font-size: 0.95rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 8px;
    color: #ffffff;
}

.syllabus-select-dropdown {
    background: rgba(255, 255, 255, 0.12);
    color: #ffffff;
    border: 1px solid rgba(255, 255, 255, 0.25);
    padding: 6px 12px;
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    font-weight: 600;
    outline: none;
    cursor: pointer;
    font-family: inherit;
    max-width: 280px;
}

.syllabus-tool-btn {
    background: rgba(255, 255, 255, 0.12);
    border: 1px solid rgba(255, 255, 255, 0.25);
    color: var(--text-on-dark);
    padding: 6px 12px;
    border-radius: var(--radius-sm);
    font-size: 0.82rem;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 4px;
    cursor: pointer;
}

.syllabus-modal-close {
    background: rgba(239, 68, 68, 0.2);
    border: 1px solid rgba(239, 68, 68, 0.4);
    color: #fca5a5;
    font-size: 1.2rem;
    padding: 4px 10px;
    border-radius: var(--radius-sm);
    cursor: pointer;
}

.syllabus-viewer-body {
    flex: 1;
    background-color: #020617;
    position: relative;
    overflow: auto;
    display: flex;
    align-items: flex-start;
    justify-content: center;
    padding: 1rem;
}

.syllabus-image-wrapper {
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 100%;
    min-height: 100%;
    transition: transform 0.15s ease-out;
    transform-origin: top center;
}

.syllabus-img {
    max-width: 100%;
    height: auto;
    object-fit: contain;
    border-radius: var(--radius-sm);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.6);
    display: block;
    margin: 0 auto;
}

.syllabus-modal-footer {
    background-color: var(--bg-card);
    border-top: 1px solid var(--border-color);
    padding: 10px 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 0.85rem;
}

/* --------------------------------------------------------------------------
   7. GLOBAL SEARCH & FLOATING CONTROLS
   -------------------------------------------------------------------------- */
.search-modal-overlay {
    position: fixed;
    inset: 0;
    background-color: rgba(2, 6, 23, 0.75);
    backdrop-filter: blur(4px);
    z-index: 2500;
    display: flex;
    align-items: flex-start;
    justify-content: center;
    padding-top: 80px;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.2s ease, visibility 0.2s ease;
}

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

.search-modal-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-strong);
    border-radius: var(--radius-lg);
    width: 100%;
    max-width: 650px;
    box-shadow: var(--shadow-xl);
    overflow: hidden;
}

.search-input-header {
    display: flex;
    align-items: center;
    padding: 1rem 1.25rem;
    border-bottom: 1px solid var(--border-color);
    gap: 12px;
}

.search-input-header input {
    flex: 1;
    border: none;
    outline: none;
    background: transparent;
    font-size: 1rem;
    color: var(--text-main);
}

.search-results-list {
    max-height: 400px;
    overflow-y: auto;
    padding: 10px;
    list-style: none;
}

.search-result-item {
    padding: 10px 14px;
    border-radius: var(--radius-sm);
    display: flex;
    flex-direction: column;
    gap: 2px;
    text-decoration: none;
}

.floating-actions {
    position: fixed;
    bottom: 24px;
    right: 24px;
    z-index: 1500;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.float-btn {
    width: 46px;
    height: 46px;
    border-radius: var(--radius-full);
    background-color: var(--accent-color);
    color: #ffffff;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.15rem;
    box-shadow: var(--shadow-lg);
}

#back-to-top {
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
}

#back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.resume-reading-banner {
    background-color: var(--accent-light);
    border: 1px solid var(--accent-color);
    border-radius: var(--radius-md);
    padding: 14px 18px;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 0.9rem;
}

/* --------------------------------------------------------------------------
   8. 🧠 QUIZ ENGINE STYLES (MODERN ACCENTS)
   -------------------------------------------------------------------------- */
.quiz-pre-modal-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-strong);
    border-radius: var(--radius-lg);
    width: 100%;
    max-width: 580px;
    padding: 2.25rem;
    box-shadow: var(--shadow-xl);
    text-align: center;
}

.quiz-breakdown-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    margin: 1.5rem 0;
}

.quiz-breakdown-card {
    background-color: var(--bg-card-alt);
    border-radius: var(--radius-md);
    padding: 14px 8px;
    display: flex;
    flex-direction: column;
    align-items: center;
    border: 1px solid var(--border-color);
}

.quiz-breakdown-card .count {
    font-size: 1.3rem;
    font-weight: 800;
}

.quiz-breakdown-card .label {
    font-size: 0.72rem;
    font-weight: 700;
    text-transform: uppercase;
}

.quiz-view-overlay {
    position: fixed;
    inset: 0;
    background-color: var(--bg-body);
    z-index: 4000;
    display: flex;
    flex-direction: column;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.25s ease, visibility 0.25s ease;
    overflow-y: auto;
}

.quiz-view-overlay.active {
    opacity: 1;
    visibility: visible;
}

.quiz-header-bar {
    background-color: var(--bg-nav);
    color: #ffffff;
    padding: 14px 1.75rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    box-shadow: var(--shadow-md);
}

.quiz-live-progress-container {
    background-color: var(--bg-card);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 1.75rem;
    max-width: 960px;
    margin: 0 auto;
    width: 100%;
}

.quiz-progress-top-info {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 0.9rem;
    font-weight: 700;
    margin-bottom: 8px;
}

.quiz-progress-bar-bg {
    width: 100%;
    height: 10px;
    background-color: var(--border-color);
    border-radius: var(--radius-full);
    overflow: hidden;
    margin-bottom: 10px;
}

.quiz-progress-bar-fill {
    height: 100%;
    background: linear-gradient(90deg, #10b981, #3b82f6, #8b5cf6, #ef4444);
    width: 0%;
    transition: width 0.3s ease;
}

.quiz-diff-pills {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 8px;
    flex-wrap: wrap;
    font-size: 0.78rem;
    font-weight: 700;
}

.quiz-pill {
    padding: 5px 12px;
    border-radius: var(--radius-full);
    background-color: var(--bg-card-alt);
    border: 1px solid var(--border-color);
}

.quiz-main-container {
    max-width: 900px;
    margin: 1.5rem auto;
    padding: 0 1rem 3rem 1rem;
    width: 100%;
}

.quiz-question-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 2.25rem;
    box-shadow: var(--shadow-md);
    margin-bottom: 1.5rem;
}

.quiz-badge {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 5px 14px;
    border-radius: var(--radius-full);
    font-size: 0.75rem;
    font-weight: 800;
    letter-spacing: 0.5px;
    margin-bottom: 1.25rem;
}

.badge-easy { background-color: #d1fae5; color: #047857; }
.badge-normal { background-color: #fef3c7; color: #b45309; }
.badge-medium { background-color: #ffedd5; color: #c2410c; }
.badge-hard { background-color: #fee2e2; color: #b91c1c; }
.badge-correct { background-color: #d1fae5; color: #047857; }
.badge-wrong { background-color: #fee2e2; color: #b91c1c; }
.badge-skipped { background-color: #f1f5f9; color: #475569; }

.quiz-options-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin: 1.5rem 0;
}

.quiz-option-btn {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 14px 20px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background-color: var(--bg-card);
    color: var(--text-main);
    font-size: 0.95rem;
    font-weight: 500;
    text-align: left;
    transition: all 0.2s ease;
    width: 100%;
}

.quiz-option-btn:hover:not([disabled]) {
    border-color: var(--accent-color);
    background-color: var(--accent-light);
}

.quiz-option-btn.selected-opt {
    border-color: var(--accent-color);
    background-color: var(--accent-light);
    font-weight: 700;
}

.quiz-option-btn.correct-opt {
    border-color: var(--success) !important;
    background-color: var(--success-bg) !important;
    color: var(--success) !important;
    font-weight: 700;
}

.quiz-option-btn.wrong-opt {
    border-color: var(--danger) !important;
    background-color: var(--danger-bg) !important;
    color: var(--danger) !important;
}

.opt-letter {
    width: 34px;
    height: 34px;
    border-radius: var(--radius-full);
    background-color: var(--bg-card-alt);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 800;
    font-size: 0.88rem;
    flex-shrink: 0;
}

.quiz-option-btn.selected-opt .opt-letter {
    background-color: var(--accent-color);
    color: #ffffff;
}

.quiz-feedback-box {
    background-color: var(--bg-card-alt);
    border-left: 5px solid var(--accent-color);
    border-radius: var(--radius-md);
    padding: 1.35rem;
    margin: 1.5rem 0;
    animation: fadeIn 0.3s ease;
}

.feedback-header {
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 8px;
    margin-bottom: 10px;
}

.feedback-why {
    font-size: 0.92rem;
    color: var(--text-muted);
}

.milestone-card {
    background-color: var(--bg-card);
    border: 2px solid var(--accent-color);
    border-radius: var(--radius-lg);
    padding: 3rem 2rem;
    text-align: center;
    box-shadow: var(--shadow-xl);
    animation: popIn 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    max-width: 600px;
    margin: 3rem auto;
}

.milestone-icon {
    font-size: 4.5rem;
    color: #f59e0b;
    margin-bottom: 1rem;
    animation: bounce 1.5s infinite;
}

.result-dashboard-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-strong);
    border-radius: var(--radius-lg);
    padding: 2.5rem;
    box-shadow: var(--shadow-xl);
    margin-bottom: 2rem;
}

.result-main-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 1.25rem;
    margin: 1.5rem 0;
}

.result-stat-box {
    background-color: var(--bg-card-alt);
    border-radius: var(--radius-md);
    padding: 1.35rem;
    text-align: center;
    border: 1px solid var(--border-color);
}

.result-stat-box .val {
    font-size: 1.9rem;
    font-weight: 800;
    color: var(--text-main);
    line-height: 1.2;
}

.result-stat-box .lbl {
    font-size: 0.8rem;
    color: var(--text-subtle);
    font-weight: 700;
}

.review-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1.35rem;
    margin-bottom: 1.25rem;
    box-shadow: var(--shadow-sm);
}

.review-card.border-success { border-left: 5px solid var(--success); }
.review-card.border-danger { border-left: 5px solid var(--danger); }
.review-card.border-subtle { border-left: 5px solid var(--text-subtle); }

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

.review-answers-grid {
    background-color: var(--bg-card-alt);
    border-radius: var(--radius-sm);
    padding: 12px 16px;
    font-size: 0.9rem;
    margin: 10px 0;
    display: flex;
    gap: 1.75rem;
    flex-wrap: wrap;
}

.review-explanation {
    font-size: 0.88rem;
    color: var(--text-muted);
    border-top: 1px dashed var(--border-color);
    padding-top: 10px;
    margin-top: 8px;
}

.review-filter-btn {
    padding: 6px 16px;
    border-radius: var(--radius-full);
    border: 1px solid var(--border-strong);
    font-size: 0.82rem;
    font-weight: 700;
    background-color: var(--bg-card);
    color: var(--text-muted);
    cursor: pointer;
}

.review-filter-btn.active {
    background-color: var(--accent-color);
    color: #ffffff;
    border-color: var(--accent-color);
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(6px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes popIn {
    from { opacity: 0; transform: scale(0.9); }
    to { opacity: 1; transform: scale(1); }
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

/* --------------------------------------------------------------------------
   9. RESPONSIVE BREAKPOINTS
   -------------------------------------------------------------------------- */
@media (max-width: 1024px) {
    .main-wrapper {
        flex-direction: column;
        padding: 1rem;
    }

    .sidebar-toc {
        position: fixed;
        inset: 0 auto 0 0;
        z-index: 2200;
        width: 300px;
        height: 100vh;
        border-radius: 0;
        transform: translateX(-100%);
        transition: transform 0.3s ease;
        top: 0;
    }

    .sidebar-toc.open {
        transform: translateX(0);
    }

    .sidebar-backdrop {
        position: fixed;
        inset: 0;
        background: rgba(0, 0, 0, 0.5);
        z-index: 2100;
        opacity: 0;
        visibility: hidden;
        transition: opacity 0.3s ease;
    }
    .sidebar-backdrop.active {
        opacity: 1;
        visibility: visible;
    }

    .mobile-nav-toggle {
        display: block;
    }
}

@media (max-width: 768px) {
    .top-navbar {
        padding: 0 1rem;
    }

    .nav-menu {
        display: none;
    }

    .page-hero {
        padding: 1.5rem;
    }

    .page-hero h1 {
        font-size: 1.5rem;
    }

    .topic-card {
        padding: 1.35rem;
    }

    .quiz-breakdown-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .quiz-diff-pills {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .nav-brand-text .title {
        font-size: 0.9rem;
    }
    .nav-brand-text .subtitle {
        display: none;
    }
    .nav-btn span {
        display: none;
    }
}