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

:root {
    /* Light theme colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --text-tertiary: #adb5bd;
    --accent-primary: #7c3aed;
    --accent-secondary: #a78bfa;
    --accent-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --border-color: #dee2e6;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --info-color: #3b82f6;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-base: 16px;
    --line-height-base: 1.6;
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
}

[data-theme="dark"] {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-tertiary: #404040;
    --text-primary: #f8f9fa;
    --text-secondary: #adb5bd;
    --text-tertiary: #6c757d;
    --border-color: #404040;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.5);
}

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

body {
    font-family: var(--font-family);
    line-height: var(--line-height-base);
    color: var(--text-primary);
    background-color: var(--bg-primary);
    transition: background-color var(--transition-base), color var(--transition-base);
}

/* ==========================================
   Typography
   ========================================== */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: var(--spacing-md);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; margin-top: var(--spacing-xl); }
h3 { font-size: 1.5rem; margin-top: var(--spacing-lg); }
h4 { font-size: 1.25rem; }

p {
    margin-bottom: var(--spacing-sm);
}

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

a:hover {
    color: var(--accent-secondary);
    text-decoration: underline;
}

/* ==========================================
   Layout
   ========================================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ==========================================
   Navigation
   ========================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: var(--bg-primary);
    box-shadow: var(--shadow-md);
    z-index: 1000;
    transition: all var(--transition-base);
}

.navbar.scrolled {
    box-shadow: var(--shadow-lg);
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-sm) var(--spacing-md);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
}

.brand-icon {
    font-size: 1.5rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-md);
    align-items: center;
}

.nav-link {
    color: var(--text-secondary);
    font-weight: 500;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: 0.5rem;
    transition: all var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
    color: var(--accent-primary);
    background: var(--bg-secondary);
    text-decoration: none;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: all var(--transition-base);
}

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

.theme-toggle,
.search-toggle {
    background: var(--bg-secondary);
    border: none;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: 0.5rem;
    cursor: pointer;
    font-size: 1.25rem;
    transition: all var(--transition-fast);
}

.theme-toggle:hover,
.search-toggle:hover {
    background: var(--bg-tertiary);
    transform: scale(1.05);
}

/* ==========================================
   Search Modal
   ========================================== */
.search-modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.8);
    z-index: 2000;
    display: none;
    align-items: flex-start;
    padding-top: 5rem;
    backdrop-filter: blur(4px);
}

.search-modal.active {
    display: flex;
}

.search-container {
    max-width: 600px;
    width: 90%;
    margin: 0 auto;
    position: relative;
}

#searchInput {
    width: 100%;
    padding: var(--spacing-md);
    font-size: 1.25rem;
    border: none;
    border-radius: 0.75rem;
    background: var(--bg-primary);
    color: var(--text-primary);
    box-shadow: var(--shadow-lg);
}

#searchClose {
    position: absolute;
    right: var(--spacing-md);
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-secondary);
}

.search-results {
    margin-top: var(--spacing-sm);
    background: var(--bg-primary);
    border-radius: 0.75rem;
    max-height: 60vh;
    overflow-y: auto;
    box-shadow: var(--shadow-lg);
}

.search-result-item {
    padding: var(--spacing-md);
    border-bottom: 1px solid var(--border-color);
    cursor: pointer;
    transition: background var(--transition-fast);
}

.search-result-item:hover {
    background: var(--bg-secondary);
}

.search-result-item:last-child {
    border-bottom: none;
}

.search-highlight {
    background: yellow;
    color: black;
    padding: 0 2px;
}

/* ==========================================
   Hero Section
   ========================================== */
.hero {
    margin-top: 70px;
    padding: var(--spacing-xl) 0;
    background: var(--accent-gradient);
    color: white;
    text-align: center;
}

.hero-title {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
    animation: fadeInUp 0.8s ease;
}

.gradient-text {
    background: linear-gradient(135deg, #fff 0%, #e0e7ff 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-sm);
    opacity: 0.9;
    animation: fadeInUp 1s ease;
}

.hero-meta {
    margin-bottom: var(--spacing-lg);
    opacity: 0.8;
    animation: fadeInUp 1.2s ease;
}

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

.meta-item a {
    color: white;
    text-decoration: underline;
}

.hero-actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
    animation: fadeInUp 1.4s ease;
}

/* ==========================================
   Buttons
   ========================================== */
.btn {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: 0.5rem;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: all var(--transition-base);
    text-decoration: none;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    text-decoration: none;
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    border: 2px solid white;
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
}

/* ==========================================
   Table of Contents Sidebar
   ========================================== */
.toc-sidebar {
    position: fixed;
    top: 0;
    right: -350px;
    width: 350px;
    height: 100vh;
    background: var(--bg-primary);
    box-shadow: var(--shadow-lg);
    z-index: 1500;
    padding: var(--spacing-lg);
    overflow-y: auto;
    transition: right var(--transition-base);
}

.toc-sidebar.active {
    right: 0;
}

.toc-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--border-color);
}

.toc-header h3 {
    margin: 0;
}

#tocClose {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-secondary);
}

.toc-nav {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.toc-link {
    display: block;
    padding: var(--spacing-xs) var(--spacing-sm);
    color: var(--text-secondary);
    border-left: 3px solid transparent;
    transition: all var(--transition-fast);
}

.toc-link:hover,
.toc-link.active {
    color: var(--accent-primary);
    background: var(--bg-secondary);
    border-left-color: var(--accent-primary);
    text-decoration: none;
}

.toc-link.toc-h3 {
    padding-left: var(--spacing-md);
    font-size: 0.9rem;
}

/* ==========================================
   Progress Bar
   ========================================== */
.progress-bar {
    position: fixed;
    top: 70px;
    left: 0;
    height: 4px;
    background: var(--accent-gradient);
    z-index: 999;
    transition: width var(--transition-fast);
}

/* ==========================================
   Main Content
   ========================================== */
.main-content {
    min-height: calc(100vh - 400px);
}

.transcript {
    max-width: 900px;
    padding: var(--spacing-xl) var(--spacing-md);
}

.section {
    margin-bottom: var(--spacing-xl);
    animation: fadeIn 0.6s ease;
}

/* ==========================================
   Content Styles
   ========================================== */
.highlight {
    background: linear-gradient(120deg, rgba(124, 58, 237, 0.1) 0%, rgba(124, 58, 237, 0.05) 100%);
    border-left: 4px solid var(--accent-primary);
    padding: var(--spacing-md);
    margin: var(--spacing-md) 0;
    border-radius: 0.5rem;
}

.callout {
    background: var(--bg-secondary);
    border: 2px solid var(--border-color);
    padding: var(--spacing-lg);
    border-radius: 0.75rem;
    margin: var(--spacing-lg) 0;
}

.info-box {
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.1) 0%, rgba(59, 130, 246, 0.05) 100%);
    border-left: 4px solid var(--info-color);
    padding: var(--spacing-md);
    border-radius: 0.5rem;
    margin: var(--spacing-md) 0;
}

.feature-list {
    list-style: none;
    padding-left: 0;
}

.feature-list li {
    padding: var(--spacing-xs) 0;
    padding-left: var(--spacing-lg);
    position: relative;
}

.feature-list li::before {
    content: "→";
    position: absolute;
    left: 0;
    color: var(--accent-primary);
    font-weight: bold;
}

.skill-type,
.trend-card {
    background: var(--bg-secondary);
    padding: var(--spacing-lg);
    border-radius: 0.75rem;
    margin: var(--spacing-md) 0;
    border: 1px solid var(--border-color);
    transition: all var(--transition-base);
}

.skill-type:hover,
.trend-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.skill-type h3,
.trend-card h3 {
    margin-top: 0;
}

.architecture-diagram {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin: var(--spacing-lg) 0;
}

.arch-component {
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 0.5rem;
    border: 2px solid var(--border-color);
    text-align: center;
    transition: all var(--transition-base);
}

.arch-component:hover {
    border-color: var(--accent-primary);
    transform: scale(1.05);
}

.arch-component h4 {
    margin-bottom: var(--spacing-sm);
    color: var(--accent-primary);
}

.comparison-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-md);
    margin: var(--spacing-lg) 0;
}

.comparison-item {
    background: var(--bg-secondary);
    padding: var(--spacing-lg);
    border-radius: 0.75rem;
    border: 2px solid var(--border-color);
    transition: all var(--transition-base);
}

.comparison-item:hover {
    border-color: var(--accent-primary);
    box-shadow: var(--shadow-md);
}

.timeline {
    position: relative;
    padding-left: var(--spacing-lg);
    margin: var(--spacing-lg) 0;
}

.timeline::before {
    content: "";
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 3px;
    background: var(--accent-gradient);
}

.timeline-item {
    position: relative;
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    background: var(--bg-secondary);
    border-radius: 0.5rem;
}

.timeline-item::before {
    content: "";
    position: absolute;
    left: calc(-1 * var(--spacing-lg) - 5px);
    top: var(--spacing-md);
    width: 15px;
    height: 15px;
    border-radius: 50%;
    background: var(--accent-primary);
    border: 3px solid var(--bg-primary);
}

.timeline-item h4 {
    margin-bottom: var(--spacing-xs);
    color: var(--accent-primary);
}

.cta-box {
    background: var(--accent-gradient);
    color: white;
    padding: var(--spacing-xl);
    border-radius: 1rem;
    text-align: center;
    margin: var(--spacing-xl) 0;
}

.cta-box h3 {
    margin-bottom: var(--spacing-md);
}

.credits {
    text-align: center;
    padding: var(--spacing-lg);
    background: var(--bg-secondary);
    border-radius: 0.75rem;
    margin-top: var(--spacing-xl);
}

.credits-author {
    font-weight: 600;
    margin-top: var(--spacing-sm);
}

/* ==========================================
   Footer
   ========================================== */
.footer {
    background: var(--bg-secondary);
    padding: var(--spacing-xl) 0 var(--spacing-md);
    margin-top: var(--spacing-xl);
}

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

.footer-section h4 {
    margin-bottom: var(--spacing-sm);
}

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

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

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--border-color);
    color: var(--text-secondary);
}

/* ==========================================
   Back to Top Button
   ========================================== */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background: var(--accent-gradient);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-lg);
    z-index: 999;
}

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

.back-to-top:hover {
    transform: translateY(-5px);
}

/* ==========================================
   Animations
   ========================================== */
@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ==========================================
   Responsive Design
   ========================================== */
@media (max-width: 768px) {
    html {
        font-size: 14px;
    }
    
    .nav-menu {
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        flex-direction: column;
        background: var(--bg-primary);
        padding: var(--spacing-md);
        box-shadow: var(--shadow-lg);
        display: none;
    }
    
    .nav-menu.active {
        display: flex;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1.25rem;
    }
    
    .toc-sidebar {
        width: 100%;
        right: -100%;
    }
    
    .architecture-diagram,
    .comparison-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    h1 { font-size: 2rem; }
    h2 { font-size: 1.5rem; }
    h3 { font-size: 1.25rem; }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .hero {
        padding: var(--spacing-lg) 0;
    }
    
    .hero-title {
        font-size: 1.75rem;
    }
    
    .back-to-top {
        width: 40px;
        height: 40px;
        bottom: 1rem;
        right: 1rem;
    }
}

/* ==========================================
   Print Styles
   ========================================== */
@media print {
    .navbar,
    .hero-actions,
    .nav-actions,
    .toc-sidebar,
    .search-modal,
    .back-to-top,
    .footer {
        display: none;
    }
    
    .hero {
        margin-top: 0;
        background: none;
        color: black;
    }
    
    .gradient-text {
        -webkit-text-fill-color: inherit;
    }
    
    body {
        font-size: 12pt;
        line-height: 1.5;
    }
}

/* ==========================================
   Accessibility
   ========================================== */
:focus-visible {
    outline: 3px solid var(--accent-primary);
    outline-offset: 2px;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

/* Reduce motion for users who prefer it */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}