/* ==============================================
   CSS Reset & Base Styles
   ============================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Primary Colors */
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --primary-light: #3b82f6;
    
    /* Medical Theme Colors */
    --medical-blue: #0ea5e9;
    --medical-teal: #14b8a6;
    --medical-green: #10b981;
    --medical-red: #ef4444;
    
    /* Neutral Colors */
    --background: #ffffff;
    --surface: #f8fafc;
    --surface-alt: #f1f5f9;
    --border: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    
    /* Semantic Colors */
    --success: #10b981;
    --warning: #f59e0b;
    --error: #ef4444;
    --info: #3b82f6;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-serif: 'Merriweather', Georgia, serif;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* Transitions */
    --transition: all 0.3s ease;
}

/* Dark Theme */
body.dark-theme {
    --background: #0f172a;
    --surface: #1e293b;
    --surface-alt: #334155;
    --border: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--background);
    transition: var(--transition);
}

.container {
    width: 100%;
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* ==============================================
   Typography
   ============================================== */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.125rem; }
h6 { font-size: 1rem; }

p {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

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

a:hover {
    color: var(--primary-dark);
}

/* ==============================================
   Header
   ============================================== */
.header {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md) 0;
    gap: var(--spacing-lg);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.logo i {
    font-size: 2rem;
    color: var(--medical-blue);
}

.logo h1 {
    font-size: 1.25rem;
    margin: 0;
    color: var(--text-primary);
}

.logo .edition {
    font-size: 0.75rem;
    color: var(--text-muted);
    background: var(--surface-alt);
    padding: 0.25rem 0.5rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
}

.main-nav {
    flex: 1;
    display: flex;
    justify-content: center;
}

.nav-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--text-primary);
    cursor: pointer;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-sm);
}

.nav-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--text-secondary);
    font-weight: 500;
    border-radius: var(--radius);
    transition: var(--transition);
}

.nav-link:hover {
    background: var(--surface-alt);
    color: var(--text-primary);
}

.nav-link.active {
    background: var(--primary-color);
    color: white;
}

.nav-link i {
    font-size: 1rem;
}

.header-actions {
    display: flex;
    gap: var(--spacing-sm);
}

.btn-icon {
    width: 2.5rem;
    height: 2.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--surface-alt);
    border: none;
    border-radius: var(--radius);
    color: var(--text-primary);
    cursor: pointer;
    transition: var(--transition);
}

.btn-icon:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-2px);
}

/* ==============================================
   Buttons
   ============================================== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: 1rem;
    font-weight: 600;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: var(--surface-alt);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background: var(--medical-blue);
    color: white;
}

.btn-outline {
    background: transparent;
    color: var(--text-primary);
    border: 2px solid var(--border);
}

.btn-outline:hover {
    background: var(--surface-alt);
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.btn-back {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    color: var(--text-primary);
    cursor: pointer;
    transition: var(--transition);
}

.btn-back:hover {
    background: var(--surface-alt);
    transform: translateX(-4px);
}

/* ==============================================
   Modal
   ============================================== */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 2000;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(4px);
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--surface);
    border-radius: var(--radius-lg);
    max-width: 600px;
    width: 90%;
    max-height: 80vh;
    overflow: hidden;
    box-shadow: var(--shadow-xl);
    animation: modalSlideIn 0.3s ease;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--border);
}

.modal-header h2 {
    font-size: 1.5rem;
    margin: 0;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
}

.modal-close:hover {
    color: var(--error);
    transform: rotate(90deg);
}

.modal-body {
    padding: var(--spacing-lg);
    max-height: calc(80vh - 80px);
    overflow-y: auto;
}

/* ==============================================
   Search
   ============================================== */
.search-input {
    width: 100%;
    padding: var(--spacing-md);
    font-size: 1rem;
    border: 2px solid var(--border);
    border-radius: var(--radius);
    background: var(--background);
    color: var(--text-primary);
    transition: var(--transition);
}

.search-input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.search-results {
    margin-top: var(--spacing-lg);
}

.search-result-item {
    padding: var(--spacing-md);
    background: var(--background);
    border-radius: var(--radius);
    margin-bottom: var(--spacing-sm);
    cursor: pointer;
    transition: var(--transition);
}

.search-result-item:hover {
    background: var(--surface-alt);
    transform: translateX(4px);
}

.search-result-item h4 {
    margin: 0 0 var(--spacing-xs) 0;
    color: var(--primary-color);
}

.search-result-item p {
    margin: 0;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

/* ==============================================
   Bookmarks
   ============================================== */
.bookmarks-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.bookmark-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md);
    background: var(--background);
    border-radius: var(--radius);
    transition: var(--transition);
}

.bookmark-item:hover {
    background: var(--surface-alt);
}

.bookmark-info {
    flex: 1;
}

.bookmark-info h4 {
    margin: 0 0 var(--spacing-xs) 0;
    color: var(--text-primary);
}

.bookmark-info p {
    margin: 0;
    font-size: 0.875rem;
    color: var(--text-muted);
}

.bookmark-actions {
    display: flex;
    gap: var(--spacing-sm);
}

.empty-state {
    text-align: center;
    padding: var(--spacing-2xl);
    color: var(--text-muted);
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
    opacity: 0.5;
}

/* ==============================================
   Hero Section
   ============================================== */
.hero-section {
    background: linear-gradient(135deg, var(--surface) 0%, var(--background) 100%);
    padding: var(--spacing-3xl) 0;
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-3xl);
    align-items: center;
}

.hero-title {
    font-size: 3rem;
    margin-bottom: var(--spacing-sm);
    background: linear-gradient(135deg, var(--primary-color), var(--medical-blue));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    font-weight: 500;
    margin-bottom: var(--spacing-lg);
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    line-height: 1.8;
}

.hero-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.stat-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--surface);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
}

.stat-item i {
    font-size: 2rem;
    color: var(--primary-color);
}

.stat-item strong {
    display: block;
    font-size: 1.25rem;
    color: var(--text-primary);
}

.stat-item span {
    display: block;
    font-size: 0.875rem;
    color: var(--text-muted);
}

.hero-actions {
    display: flex;
    gap: var(--spacing-md);
}

.hero-image {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
}

.hero-card {
    padding: var(--spacing-xl);
    background: white;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    transition: var(--transition);
}

.hero-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
}

.hero-card i {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
}

.hero-card h4 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-sm);
}

.hero-card p {
    margin: 0;
    color: var(--text-secondary);
}

/* ==============================================
   Sections
   ============================================== */
.section {
    padding: var(--spacing-3xl) 0;
}

.section:nth-child(even) {
    background: var(--surface);
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
}

.section-title {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.section-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* ==============================================
   About Section
   ============================================== */
.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-3xl);
}

.about-text h3 {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-xl);
    color: var(--primary-color);
}

.about-text h3:first-child {
    margin-top: 0;
}

.objectives-list {
    list-style: none;
    margin-bottom: var(--spacing-xl);
}

.objectives-list li {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) 0;
    color: var(--text-secondary);
}

.objectives-list i {
    color: var(--success);
    font-size: 1.25rem;
}

.target-audience {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.audience-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md);
    background: var(--surface);
    border-radius: var(--radius);
    color: var(--text-primary);
    font-weight: 500;
}

.audience-item i {
    font-size: 1.5rem;
    color: var(--medical-blue);
}

.about-highlights {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.highlight-card {
    padding: var(--spacing-xl);
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.highlight-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.highlight-icon {
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--primary-color), var(--medical-blue));
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-md);
}

.highlight-icon i {
    font-size: 2rem;
    color: white;
}

.highlight-card h4 {
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.highlight-card p {
    margin: 0;
    color: var(--text-secondary);
}

/* ==============================================
   Chapters Section
   ============================================== */
.chapters-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
    gap: var(--spacing-2xl);
    padding: var(--spacing-md);
}

.chapter-card {
    position: relative;
    background: white;
    border-radius: var(--radius-xl);
    padding: 0;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    cursor: pointer;
    border: 2px solid transparent;
    overflow: hidden;
}

.chapter-card:hover {
    transform: translateY(-12px) scale(1.02);
    box-shadow: 0 20px 40px rgba(0,0,0,0.15), 0 0 0 1px rgba(59, 130, 246, 0.1);
    border-color: var(--primary-color);
}

.chapter-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, transparent 0%, rgba(255,255,255,0.05) 100%);
    opacity: 0;
    transition: opacity 0.3s ease;
    pointer-events: none;
    border-radius: var(--radius-xl);
}

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

.chapter-icon {
    width: 100%;
    height: 120px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--primary-color), var(--medical-blue));
    position: relative;
    overflow: hidden;
}

.chapter-icon::before {
    content: '';
    position: absolute;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: pulse 3s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
        opacity: 0.5;
    }
    50% {
        transform: scale(1.1);
        opacity: 0.8;
    }
}

.chapter-icon i {
    font-size: 3.5rem;
    color: white;
    position: relative;
    z-index: 1;
    filter: drop-shadow(0 4px 8px rgba(0,0,0,0.2));
}

.chapter-card > * {
    padding: 0 var(--spacing-xl);
}

.chapter-card > .chapter-icon {
    padding: 0;
}

.chapter-number {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--primary-color);
    color: white;
    border-radius: 0 0 var(--radius-lg) 0;
    font-weight: 700;
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin: 0;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 2;
}

.chapter-card h3 {
    font-size: 1.5rem;
    margin: var(--spacing-lg) 0 var(--spacing-md);
    color: var(--text-primary);
    font-weight: 700;
    line-height: 1.3;
}

.chapter-card p {
    margin-bottom: var(--spacing-lg);
    color: var(--text-secondary);
    line-height: 1.7;
    font-size: 0.9375rem;
}

.chapter-meta {
    display: flex;
    gap: var(--spacing-lg);
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: 0.875rem;
    color: var(--text-muted);
    background: var(--surface);
}

.chapter-meta span {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.chapter-meta i {
    color: var(--primary-color);
    font-size: 1rem;
}

.chapter-footer {
    padding: var(--spacing-md) var(--spacing-xl);
    border-top: 3px solid var(--primary-color);
    background: white;
    margin: 0;
}

.read-more {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-weight: 600;
    color: var(--primary-color);
    font-size: 0.9375rem;
    transition: var(--transition);
}

.chapter-card:hover .read-more {
    gap: var(--spacing-md);
}

.chapter-card:hover .read-more i {
    transform: translateX(4px);
}

/* Dark theme adjustments for chapters */
body.dark-theme .chapter-card {
    background: var(--surface);
}

body.dark-theme .chapter-meta {
    background: var(--surface-alt);
}

body.dark-theme .chapter-footer {
    background: var(--surface);
}

/* Chapter card badge for new content */
.chapter-badge {
    position: absolute;
    top: var(--spacing-md);
    right: var(--spacing-md);
    background: var(--success);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-xl);
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    z-index: 3;
    box-shadow: 0 2px 8px rgba(0,0,0,0.2);
}

/* Chapter progress indicator (for future use) */
.chapter-progress {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: rgba(0,0,0,0.1);
}

.chapter-progress-bar {
    height: 100%;
    background: var(--success);
    transition: width 0.3s ease;
}

/* ==============================================
   Chapter Detail
   ============================================== */
.chapter-content {
    max-width: 900px;
    margin: 0 auto;
}

.chapter-header {
    margin-bottom: var(--spacing-2xl);
}

.chapter-header .chapter-number {
    font-size: 1.25rem;
}

.chapter-header h1 {
    font-size: 2.5rem;
    margin: var(--spacing-lg) 0;
}

.chapter-intro {
    font-size: 1.125rem;
    color: var(--text-secondary);
    line-height: 1.8;
    padding: var(--spacing-xl);
    background: var(--surface);
    border-left: 4px solid var(--primary-color);
    border-radius: var(--radius);
    margin-bottom: var(--spacing-2xl);
}

.chapter-section {
    margin-bottom: var(--spacing-3xl);
}

.chapter-section h2 {
    font-size: 2rem;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--border);
}

.chapter-section h3 {
    font-size: 1.5rem;
    margin: var(--spacing-xl) 0 var(--spacing-md);
    color: var(--primary-color);
}

.chapter-section ul, .chapter-section ol {
    margin-left: var(--spacing-xl);
    margin-bottom: var(--spacing-lg);
}

.chapter-section li {
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
    line-height: 1.8;
}

.info-box {
    padding: var(--spacing-lg);
    background: var(--surface);
    border-left: 4px solid var(--info);
    border-radius: var(--radius);
    margin: var(--spacing-xl) 0;
}

.info-box.warning {
    border-left-color: var(--warning);
}

.info-box.success {
    border-left-color: var(--success);
}

.info-box.error {
    border-left-color: var(--error);
}

.info-box h4 {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
}

.info-box p {
    margin: 0;
}

.table-wrapper {
    overflow-x: auto;
    margin: var(--spacing-xl) 0;
}

table {
    width: 100%;
    border-collapse: collapse;
    background: white;
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
}

thead {
    background: var(--primary-color);
    color: white;
}

th, td {
    padding: var(--spacing-md);
    text-align: left;
    border-bottom: 1px solid var(--border);
}

th {
    font-weight: 600;
}

tbody tr:hover {
    background: var(--surface);
}

/* ==============================================
   Resources Section
   ============================================== */
.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-xl);
}

.resource-card {
    background: white;
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: var(--transition);
}

.resource-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
}

.resource-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto var(--spacing-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--primary-color), var(--medical-blue));
    border-radius: var(--radius-xl);
}

.resource-icon i {
    font-size: 2.5rem;
    color: white;
}

.resource-card h3 {
    margin-bottom: var(--spacing-md);
}

.resource-card p {
    margin-bottom: var(--spacing-lg);
    color: var(--text-secondary);
}

/* ==============================================
   References Section
   ============================================== */
.references-intro {
    max-width: 800px;
    margin: 0 auto var(--spacing-2xl);
    text-align: center;
    font-size: 1.125rem;
}

.references-list {
    max-width: 900px;
    margin: 0 auto;
}

.reference-item {
    display: flex;
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    background: white;
    border-radius: var(--radius);
    margin-bottom: var(--spacing-md);
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.reference-item:hover {
    box-shadow: var(--shadow-md);
    transform: translateX(4px);
}

.ref-number {
    flex-shrink: 0;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--primary-color);
    color: white;
    border-radius: var(--radius);
    font-weight: 700;
}

.reference-item p {
    margin: 0;
    font-size: 0.9375rem;
    line-height: 1.6;
    color: var(--text-secondary);
}

/* ==============================================
   Footer
   ============================================== */
.footer {
    background: var(--surface);
    border-top: 1px solid var(--border);
    padding: var(--spacing-3xl) 0 var(--spacing-xl);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-2xl);
}

.footer-section h3, .footer-section h4 {
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.footer-section h3 {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 1.25rem;
}

.footer-section h3 i {
    color: var(--medical-blue);
}

.footer-section p {
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: var(--spacing-sm);
}

.footer-section ul a {
    color: var(--text-secondary);
    transition: var(--transition);
}

.footer-section ul a:hover {
    color: var(--primary-color);
    padding-left: var(--spacing-xs);
}

.copyright {
    margin-top: var(--spacing-lg);
    font-size: 0.875rem;
    color: var(--text-muted);
}

.disclaimer {
    font-size: 0.875rem;
    padding: var(--spacing-md);
    background: var(--surface-alt);
    border-radius: var(--radius);
    border-left: 3px solid var(--warning);
}

/* ==============================================
   Responsive Design
   ============================================== */
@media (max-width: 1024px) {
    .hero-content {
        grid-template-columns: 1fr;
    }
    
    .about-content {
        grid-template-columns: 1fr;
    }
    
    .chapters-grid {
        grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    }
}

@media (max-width: 768px) {
    .nav-toggle {
        display: block;
    }
    
    .nav-menu {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        background: var(--surface);
        border-top: 1px solid var(--border);
        padding: var(--spacing-md);
        display: none;
        box-shadow: var(--shadow-lg);
    }
    
    .nav-menu.active {
        display: flex;
    }
    
    .header-actions {
        display: none;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1.25rem;
    }
    
    .hero-stats {
        grid-template-columns: 1fr;
    }
    
    .hero-actions {
        flex-direction: column;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .target-audience {
        grid-template-columns: 1fr;
    }
    
    .chapters-grid {
        grid-template-columns: 1fr;
    }
    
    .resources-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .logo h1 {
        font-size: 1rem;
    }
    
    .hero-title {
        font-size: 1.75rem;
    }
    
    .chapter-card {
        padding: var(--spacing-lg);
    }
}

/* ==============================================
   Animations
   ============================================== */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in {
    animation: fadeIn 0.6s ease;
}

/* ==============================================
   Image Gallery
   ============================================== */
.gallery-section {
    background: var(--background);
}

.gallery-category {
    margin-bottom: var(--spacing-3xl);
}

.gallery-item {
    transition: var(--transition);
}

.gallery-item:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl) !important;
}

.image-grid {
    animation: fadeIn 0.6s ease;
}

.chapter-image {
    margin: var(--spacing-2xl) 0;
}

.chapter-image img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    display: block;
    margin: 0 auto;
}

.image-caption {
    margin-top: var(--spacing-md);
    font-size: 0.875rem;
    color: var(--text-muted);
    font-style: italic;
    text-align: center;
    line-height: 1.6;
}

.image-caption strong {
    color: var(--text-secondary);
    font-weight: 600;
}

/* Image Modal Specific Styles */
#imageModal .modal-content {
    max-width: 90vw;
    max-height: 90vh;
}

#imageModal .modal-body {
    padding: 0;
    overflow: auto;
    max-height: calc(90vh - 80px);
}

#imageModal img {
    width: 100%;
    height: auto;
    display: block;
}

/* ==============================================
   Print Styles
   ============================================== */
@media print {
    .header, .footer, .nav-toggle, .header-actions {
        display: none;
    }
    
    .section {
        page-break-inside: avoid;
    }
    
    a {
        text-decoration: underline;
    }
    
    .chapter-image img {
        max-width: 100%;
        page-break-inside: avoid;
    }
}