/* ============================================
   AI4SocialScience - Minimal White Theme
   Clean white, black, and blue palette
   ============================================ */

/* CSS Variables */
:root {
    /* ===== Primary Surfaces - Clean White ===== */
    --bg-primary: #FFFFFF;
    --bg-secondary: #F9FAFB;
    --bg-tertiary: #F3F4F6;
    --bg-elevated: #FFFFFF;

    /* Background Gradient - Clean solid */
    --bg-gradient: linear-gradient(180deg, #FFFFFF 0%, #F9FAFB 100%);

    /* Neutral Grays */
    --gray-50: #ffffff;
    --gray-100: #f9fafb;
    --gray-200: #f3f4f6;
    --gray-300: #e5e7eb;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;

    /* ===== Text Colors ===== */
    --text-primary: #111827;
    --text-secondary: #4B5563;
    --text-tertiary: #9CA3AF;
    --text-inverse: #FFFFFF;

    /* ===== Primary Accent - Black ===== */
    --accent-primary: #111827;
    --accent-primary-light: #374151;
    --accent-primary-dark: #000000;
    --accent-primary-50: rgba(17, 24, 39, 0.05);
    --accent-primary-100: rgba(17, 24, 39, 0.1);
    --accent-primary-200: rgba(17, 24, 39, 0.2);
    --accent-primary-300: rgba(17, 24, 39, 0.3);

    /* ===== Secondary Accent - Blue ===== */
    --accent-secondary: #2563EB;
    --accent-secondary-light: #3B82F6;
    --accent-secondary-dark: #1D4ED8;
    --accent-secondary-100: rgba(37, 99, 235, 0.1);
    --accent-secondary-200: rgba(37, 99, 235, 0.2);

    /* ===== Tertiary ===== */
    --accent-tertiary: #6366F1;
    --accent-tertiary-light: #818CF8;
    --accent-tertiary-dark: #4F46E5;

    /* ===== Gradients ===== */
    --accent-gradient: linear-gradient(135deg, #111827 0%, #2563EB 100%);
    --gradient-warm: linear-gradient(135deg, #111827 0%, #374151 100%);
    --gradient-cool: linear-gradient(135deg, #111827 0%, #2563EB 100%);
    --gradient-mesh:
        radial-gradient(ellipse at 20% 30%, rgba(37, 99, 235, 0.08) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 20%, rgba(17, 24, 39, 0.06) 0%, transparent 50%);

    /* ===== Hero Entrance Animation Delays ===== */
    --hero-delay-1: 0.1s;
    --hero-delay-2: 0.25s;
    --hero-delay-3: 0.4s;
    --hero-delay-4: 0.55s;
    --hero-delay-5: 0.7s;
    --hero-delay-6: 0.85s;

    /* ===== Glow Effects ===== */
    --accent-glow: rgba(37, 99, 235, 0.3);
    --accent-glow-strong: 0 0 25px rgba(37, 99, 235, 0.3);
    --accent-secondary-glow: rgba(37, 99, 235, 0.25);

    /* ===== Alias Variables (backward compatibility) ===== */
    --border-color: rgba(17, 24, 39, 0.1);
    --text-muted: #9CA3AF;

    /* ===== Semantic Colors ===== */
    --success: #059669;
    --success-light: #10B981;
    --success-bg: rgba(5, 150, 105, 0.1);
    --success-border: rgba(5, 150, 105, 0.2);

    --warning: #D97706;
    --warning-light: #F59E0B;
    --warning-bg: rgba(217, 119, 6, 0.1);
    --warning-border: rgba(217, 119, 6, 0.2);

    --error: #DC2626;
    --error-light: #EF4444;
    --error-bg: rgba(220, 38, 38, 0.1);
    --error-border: rgba(220, 38, 38, 0.2);

    --info: #2563EB;
    --info-light: #3B82F6;
    --info-bg: rgba(37, 99, 235, 0.1);
    --info-border: rgba(37, 99, 235, 0.2);

    /* ===== Borders ===== */
    --border-subtle: rgba(17, 24, 39, 0.05);
    --border-default: rgba(17, 24, 39, 0.1);
    --border-strong: rgba(17, 24, 39, 0.2);
    --border-accent: rgba(37, 99, 235, 0.4);

    /* ===== Glass Effect (Minimal) ===== */
    --glass-bg: rgba(255, 255, 255, 0.8);
    --glass-border: rgba(17, 24, 39, 0.08);
    --glass-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
    --glass-hover: rgba(255, 255, 255, 0.95);

    /* ===== Shadows (Minimal) ===== */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.12);

    /* ===== Border Radius ===== */
    --border-radius: 12px;
    --border-radius-sm: 8px;
    --border-radius-md: 12px;
    --border-radius-lg: 20px;
    --border-radius-xl: 28px;
    --border-radius-full: 9999px;

    /* ===== Typography ===== */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-heading: 'Inter', -apple-system, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

    /* ===== Type Scale ===== */
    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.125rem;
    --text-xl: 1.25rem;
    --text-2xl: 1.5rem;
    --text-3xl: 1.875rem;
    --text-4xl: 2.25rem;
    --text-5xl: 3rem;
    --text-6xl: 3.75rem;

    /* ===== Font Weights ===== */
    --font-light: 300;
    --font-regular: 400;
    --font-medium: 500;
    --font-semibold: 600;
    --font-bold: 700;
    --font-extrabold: 800;

    /* ===== Line Heights ===== */
    --leading-none: 1;
    --leading-tight: 1.25;
    --leading-snug: 1.375;
    --leading-normal: 1.5;
    --leading-relaxed: 1.625;

    /* ===== Letter Spacing ===== */
    --tracking-tight: -0.025em;
    --tracking-normal: 0;
    --tracking-wide: 0.025em;

    /* ===== Spacing ===== */
    --space-0: 0;
    --space-px: 1px;
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;
    --space-16: 4rem;
    --space-20: 5rem;
    --space-24: 6rem;

    /* Semantic Spacing */
    --space-xs: 0.5rem;
    --space-sm: 0.75rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2.5rem;
    --space-2xl: 3.5rem;
    --space-3xl: 5rem;

    /* ===== Transitions ===== */
    --duration-instant: 50ms;
    --duration-fast: 150ms;
    --duration-base: 250ms;
    --duration-slow: 400ms;

    --ease-linear: linear;
    --ease-out: cubic-bezier(0, 0, 0.2, 1);
    --ease-in-out: cubic-bezier(0.4, 0, 0.2, 1);
    --ease-spring: cubic-bezier(0.68, -0.55, 0.265, 1.55);

    --transition-fast: all var(--duration-fast) var(--ease-out);
    --transition-base: all var(--duration-base) var(--ease-out);
    --transition-smooth: transform var(--duration-base) var(--ease-out),
        opacity var(--duration-base) var(--ease-out);
    --transition-bounce: all var(--duration-base) var(--ease-spring);
}

/* Reset & Base */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    background: var(--bg-gradient);
    background-attachment: fixed;
    color: var(--text-primary);
    line-height: var(--leading-normal);
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
    letter-spacing: 0.01em;
}

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

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

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

/* ============================================
   Scroll Reveal Animations
   ============================================ */
.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* ============================================
   Navigation
   ============================================ */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-default);
    transition: all var(--transition-base);
}

.nav.scrolled {
    background: rgba(255, 255, 255, 0.98);
    box-shadow: var(--shadow-sm);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--space-md) var(--space-lg);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

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

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

.nav-links {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    flex-wrap: wrap;
}

.nav-links a {
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    position: relative;
    padding: 0.25rem 0;
    transition: color var(--transition-fast);
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--text-primary);
}

/* 横线仅在选中时显示 */
.nav-links a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent-secondary);
    transition: width var(--duration-base) var(--ease-out);
    border-radius: 1px;
}

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

.nav-lang {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-default);
    border-radius: var(--border-radius-sm);
    padding: 0.25rem 0.7rem;
    line-height: 1.2;
    font-size: 0.85rem;
    transition: all var(--transition-fast);
}

.nav-lang:hover {
    background: var(--accent-secondary-100);
    border-color: var(--accent-secondary);
    color: var(--accent-secondary);
}

.nav-cta {
    background: var(--accent-primary);
    padding: 0.5rem 1.25rem;
    border-radius: var(--border-radius-full);
    color: white;
    transition: all var(--transition-base);
    font-weight: 600;
    font-size: 0.9rem;
}

.nav-cta:hover {
    background: var(--accent-secondary);
    color: white;
}

.nav-cta::after {
    display: none;
}

/* Mobile hamburger */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.nav-toggle span {
    display: block;
    width: 20px;
    height: 2px;
    background: var(--text-primary);
    margin: 4px 0;
    transition: all var(--duration-base);
    border-radius: 2px;
}

.nav-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(4px, 4px);
}

.nav-toggle.active span:nth-child(2) {
    opacity: 0;
}

.nav-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(4px, -4px);
}

.section {
    padding: var(--space-3xl) 0;
}

/* ============================================
   Hero Section
   ============================================ */
.hero {
    min-height: 90vh;
    display: grid;
    grid-template-columns: 1fr 1fr;
    align-items: center;
    gap: var(--space-3xl);
    padding: calc(100px + var(--space-3xl)) var(--space-lg) var(--space-3xl);
    max-width: 1400px;
    margin: 0 auto;
    position: relative;
}

.hero::before {
    content: '';
    position: absolute;
    top: -30%;
    left: -20%;
    width: 140%;
    height: 160%;
    background:
        radial-gradient(ellipse at 30% 40%, rgba(37, 99, 235, 0.06) 0%, transparent 50%),
        radial-gradient(ellipse at 70% 30%, rgba(17, 24, 39, 0.04) 0%, transparent 50%);
    animation: gentleFloat 25s ease-in-out infinite;
    z-index: -1;
    pointer-events: none;
}

.hero-badge {
    display: inline-block;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-default);
    padding: 0.4rem 1rem;
    border-radius: var(--border-radius-full);
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: var(--space-lg);
    font-weight: 500;
}

.hero-title {
    font-family: var(--font-heading);
    font-size: clamp(2.5rem, 5vw, 3.5rem);
    font-weight: 800;
    line-height: 1.15;
    margin-bottom: var(--space-lg);
    color: var(--text-primary);
    letter-spacing: -0.03em;
}

.gradient-text {
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-description {
    font-size: 1.15rem;
    color: var(--text-secondary);
    margin-bottom: var(--space-xl);
    max-width: 500px;
    line-height: 1.7;
}

.hero-actions {
    display: flex;
    gap: var(--space-md);
    margin-bottom: var(--space-2xl);
    flex-wrap: wrap;
    align-items: center;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius-full);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    border: none;
    font-size: var(--text-base);
    letter-spacing: 0.02em;
}

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

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

.btn-secondary {
    background: white;
    border: 1.5px solid var(--border-default);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background: var(--bg-tertiary);
    border-color: var(--accent-primary);
    color: var(--accent-primary);
    transform: translateY(-2px);
}

/* Stats */
.hero-stats {
    display: flex;
    gap: var(--space-xl);
    flex-wrap: wrap;
}

.stat {
    min-width: 90px;
}

.stat-value {
    font-family: var(--font-heading);
    font-size: 2rem;
    font-weight: 800;
    color: var(--text-primary);
    line-height: 1;
}

.stat-label {
    display: block;
    color: var(--text-tertiary);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    margin-top: 0.35rem;
}

/* Code Preview */
.code-preview {
    background: var(--gray-900);
    border: 1px solid var(--gray-800);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    width: 100%;
    max-width: 480px;
    box-shadow: var(--shadow-xl);
}

.code-header {
    background: var(--gray-800);
    padding: var(--space-md);
    display: flex;
    align-items: center;
    gap: 8px;
}

.code-dot {
    width: 11px;
    height: 11px;
    border-radius: 50%;
}

.code-dot.red {
    background: #ff6b6b;
}

.code-dot.yellow {
    background: #ffd93d;
}

.code-dot.green {
    background: #6bcb77;
}

.code-title {
    margin-left: auto;
    color: var(--gray-400);
    font-size: 0.75rem;
    font-family: var(--font-mono);
}

.code-content {
    padding: var(--space-lg);
    color: #e0e0e0;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    line-height: 1.6;
}

/* ============================================
   Cards
   ============================================ */
.section-title {
    font-family: var(--font-heading);
    font-size: 2rem;
    text-align: center;
    margin-bottom: var(--space-sm);
    color: var(--text-primary);
    letter-spacing: -0.02em;
    font-weight: 700;
}

.section-description {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: var(--space-xl);
    font-size: 1rem;
}

.filter-tabs {
    display: flex;
    justify-content: center;
    gap: var(--space-sm);
    margin-bottom: var(--space-xl);
    flex-wrap: wrap;
}

.filter-tab {
    background: white;
    border: 1px solid var(--border-default);
    padding: 0.45rem 0.9rem;
    border-radius: var(--border-radius-full);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-base);
    font-size: 0.85rem;
    font-weight: 500;
    white-space: nowrap;
}

.filter-tab:hover {
    background: var(--bg-tertiary);
    border-color: var(--border-strong);
    color: var(--text-primary);
}

.filter-tab.active {
    background: var(--accent-primary);
    color: white;
    border-color: var(--accent-primary);
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--space-xl);
}

.skill-card {
    background: white;
    border: 1px solid var(--border-default);
    border-radius: var(--border-radius);
    padding: var(--space-xl);
    box-shadow: var(--shadow-sm);
    position: relative;
    display: flex;
    flex-direction: column;
    border-left: 3px solid transparent;
    transition: all 0.3s var(--ease-out), border-left-color 0.3s var(--ease-out);
}

.skill-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 20px 40px rgba(37, 99, 235, 0.1), var(--shadow-md);
    border-color: var(--accent-secondary-200);
    border-left-color: var(--accent-secondary);
}

.skill-icon {
    font-size: 2rem;
    margin-bottom: var(--space-sm);
    display: block;
}

.skill-title {
    font-family: var(--font-heading);
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: var(--space-xs);
    color: var(--text-primary);
}

.skill-description {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
    margin-bottom: var(--space-md);
}

.tag {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    padding: 4px 10px;
    border-radius: var(--border-radius-sm);
    font-size: 0.75rem;
    font-weight: 600;
    border: 1px solid var(--border-default);
    transition: all var(--transition-fast);
}

.tag:hover {
    background: var(--accent-secondary-100);
    color: var(--accent-secondary);
    border-color: var(--accent-secondary-200);
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
}

.skill-footer {
    margin-top: auto;
    padding-top: var(--space-md);
    border-top: 1px solid var(--border-subtle);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.skill-link {
    color: var(--accent-secondary);
    font-weight: 600;
    transition: all var(--transition-fast);
}

.skill-link:hover {
    color: var(--accent-primary);
    transform: translateX(3px);
}

.status {
    text-transform: capitalize;
    color: var(--text-tertiary);
    font-size: 0.8rem;
}

/* ============================================
   Taxonomy
   ============================================ */
.taxonomy-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-xl);
}

.taxonomy-card {
    background: white;
    border: 1px solid var(--border-default);
    border-radius: var(--border-radius);
    padding: var(--space-xl);
    box-shadow: var(--shadow-sm);
    transition: all var(--duration-base);
}

.taxonomy-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--accent-secondary-200);
}

.taxonomy-card h3 {
    font-family: var(--font-heading);
    margin-bottom: var(--space-sm);
    color: var(--text-primary);
    font-weight: 700;
}

.taxonomy-card p {
    color: var(--text-secondary);
    margin-bottom: var(--space-md);
    line-height: 1.6;
}

/* ============================================
   Quick Start
   ============================================ */
.quickstart-section {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-subtle);
    border-bottom: 1px solid var(--border-subtle);
}

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

.step {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: var(--space-xl);
    margin-bottom: var(--space-2xl);
}

.step:last-child {
    margin-bottom: 0;
}

.step-number {
    width: 48px;
    height: 48px;
    background: var(--accent-primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 700;
    font-size: 1.1rem;
    flex-shrink: 0;
}

.step-content h3 {
    font-family: var(--font-heading);
    margin-bottom: var(--space-sm);
    color: var(--text-primary);
    font-weight: 700;
}

.step-content p {
    color: var(--text-secondary);
    margin-bottom: var(--space-md);
    line-height: 1.7;
}

.tool-grid {
    display: flex;
    gap: var(--space-md);
    flex-wrap: wrap;
}

.tool-card {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    background: white;
    border: 1px solid var(--border-default);
    padding: 0.65rem 1.1rem;
    border-radius: var(--border-radius-sm);
    transition: all var(--transition-base);
    color: var(--text-secondary);
    font-weight: 500;
}

.tool-card:hover {
    border-color: var(--accent-secondary);
    color: var(--accent-secondary);
    transform: translateY(-2px);
}

.tool-icon {
    font-size: 1.25rem;
}

.code-block {
    background: var(--gray-900);
    border-radius: var(--border-radius-sm);
    padding: var(--space-md);
    overflow-x: auto;
    border: 1px solid var(--gray-800);
}

.code-block code {
    color: #e0e0e0;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    white-space: pre;
    line-height: 1.6;
}

.code-block .comment {
    color: var(--gray-500);
}

/* ============================================
   Author Section
   ============================================ */
.author-section {
    background: var(--bg-secondary);
    border: 1px solid var(--border-subtle);
    border-radius: var(--border-radius-lg);
    padding: var(--space-3xl);
    margin: var(--space-3xl) auto;
    max-width: 1000px;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: var(--space-3xl);
    align-items: center;
}

.author-section img {
    width: 150px;
    border-radius: var(--border-radius-md);
    border: 1px solid var(--border-subtle);
}

.author-content h3 {
    font-family: var(--font-heading);
    margin-bottom: var(--space-sm);
    color: var(--text-primary);
    font-weight: 700;
}

.author-content a {
    color: var(--accent-secondary);
}

.author-links {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-md);
    margin-top: var(--space-md);
}

.author-link {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-default);
    border-radius: var(--border-radius-full);
    padding: 0.35rem 0.75rem;
    color: var(--text-secondary);
    font-size: 0.85rem;
    transition: all var(--transition-fast);
}

.author-link:hover {
    background: var(--accent-secondary-100);
    border-color: var(--accent-secondary-200);
    color: var(--accent-secondary);
}

.author-icon {
    width: 16px;
    height: 16px;
    display: inline-block;
    flex: 0 0 auto;
}

.author-wechat-label {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.4rem;
    color: var(--text-secondary);
    margin-bottom: var(--space-md);
    font-size: 0.9rem;
}

/* ============================================
   Footer
   ============================================ */
.footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-subtle);
    padding: var(--space-2xl) 0;
    margin-top: var(--space-3xl);
}

.footer p,
.footer strong {
    color: var(--text-secondary);
}

.footer-links a {
    color: var(--text-tertiary);
    margin-left: var(--space-lg);
    transition: color var(--transition-fast);
    font-size: 0.9rem;
}

.footer-content {
    text-align: center;
}

.footer-links {
    display: flex;
    justify-content: center;
}

.footer-links a:hover {
    color: var(--accent-secondary);
}

/* ============================================
   Particle Canvas
   ============================================ */
#particle-canvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    pointer-events: none;
    opacity: 0.25;
}

/* ============================================
   Responsive Design
   ============================================ */

/* Tablet breakpoint */
@media (max-width: 1024px) {
    .hero {
        grid-template-columns: 1fr;
        text-align: center;
        gap: var(--space-xl);
    }

    .hero-content {
        order: 1;
    }

    .hero-visual {
        order: 2;
        max-width: 500px;
        margin: 0 auto;
    }

    .hero-actions {
        justify-content: center;
    }

    .hero-stats {
        justify-content: center;
    }

    .skills-grid {
        grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
        gap: var(--space-md);
    }
}

@media (max-width: 768px) {
    .hero {
        grid-template-columns: 1fr;
        text-align: center;
        padding-top: 120px;
        min-height: auto;
    }

    .hero-description {
        margin-left: auto;
        margin-right: auto;
    }

    .hero-actions {
        justify-content: center;
    }

    .hero-stats {
        justify-content: center;
    }

    .hero-visual {
        display: none;
    }

    .nav-links {
        position: fixed;
        top: 60px;
        left: 0;
        right: 0;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(20px);
        flex-direction: column;
        display: flex;
        gap: var(--space-md);
        border-bottom: 1px solid var(--border-subtle);
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.3s ease-out, padding 0.3s ease-out;
        padding: 0;
    }

    .nav-links.open {
        max-height: 500px;
        padding: 1rem 0;
    }

    .nav-toggle {
        display: block;
    }

    .section-title {
        font-size: 1.75rem;
    }

    .step {
        grid-template-columns: 1fr;
        gap: var(--space-md);
    }

    .step-number {
        width: 40px;
        height: 40px;
    }

    .tool-grid {
        flex-direction: column;
    }

    .skills-grid {
        grid-template-columns: 1fr;
    }

    .taxonomy-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 1.75rem;
    }

    .hero-actions {
        flex-direction: column;
        align-items: center;
    }

    .btn {
        width: 100%;
        justify-content: center;
        margin-bottom: var(--space-sm);
    }

    .filter-tabs {
        gap: 0.3rem;
    }

    .filter-tab {
        font-size: 0.8rem;
        padding: 0.35rem 0.7rem;
    }
}

/* ============================================
   Detail Pages
   ============================================ */
.detail-header {
    padding: calc(80px + var(--space-3xl)) var(--space-lg) var(--space-2xl);
    max-width: 900px;
    margin: 0 auto;
}

.detail-title {
    font-family: var(--font-heading);
    font-size: 2rem;
    margin: var(--space-md) 0;
    letter-spacing: -0.02em;
    color: var(--text-primary);
}

.detail-description {
    font-size: 1.2rem;
    color: var(--text-secondary);
}

.detail-meta {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
    margin: var(--space-lg) 0;
}

.meta-tag {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-default);
    padding: 4px 12px;
    border-radius: var(--border-radius-sm);
    font-size: 0.8rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.detail-actions {
    display: flex;
    gap: var(--space-md);
    margin-top: var(--space-lg);
    flex-wrap: wrap;
}

.detail-content {
    max-width: 900px;
    margin: 0 auto;
    padding: var(--space-2xl) var(--space-lg);
    color: var(--text-secondary);
    line-height: 1.8;
}

.detail-content h1,
.detail-content h2,
.detail-content h3 {
    color: var(--text-primary);
    font-family: var(--font-heading);
    margin-top: var(--space-2xl);
    margin-bottom: var(--space-md);
}

.detail-content pre {
    background: var(--gray-900);
    border: 1px solid var(--gray-800);
    border-radius: var(--border-radius-sm);
    padding: var(--space-lg);
    overflow-x: auto;
    margin: var(--space-lg) 0;
}

.detail-content code {
    font-family: var(--font-mono);
    font-size: 0.9rem;
    color: #e0e0e0;
}

.detail-content a {
    color: var(--accent-secondary);
}

.detail-content a:hover {
    text-decoration: underline;
}

/* ============================================
   Print Styles
   ============================================ */
@media print {
    :root {
        --bg-primary: #ffffff;
        --bg-secondary: #f9fafb;
        --bg-gradient: none;
        --text-primary: #111827;
        --text-secondary: #4b5563;
    }

    body {
        background: white !important;
        color: #111827 !important;
    }

    .nav,
    .footer,
    .hero-visual,
    #particle-canvas,
    .btn,
    .filter-tabs,
    .hero-actions,
    .nav-toggle {
        display: none !important;
    }

    .hero {
        padding: 20px 0;
        min-height: auto;
        display: block;
        text-align: left;
    }

    .hero-title {
        font-size: 1.75rem;
        color: #111827 !important;
    }

    .gradient-text {
        background: none;
        -webkit-text-fill-color: #2563EB;
        color: #2563EB !important;
    }

    .section {
        padding: 20px 0;
    }

    .skills-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 12px;
    }

    .skill-card {
        background: white !important;
        border: 1px solid #e5e7eb !important;
        box-shadow: none !important;
        break-inside: avoid;
    }

    .section-title,
    .skill-title {
        color: #111827 !important;
    }

    a {
        color: #2563EB !important;
        text-decoration: underline;
    }
}

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

a:focus-visible,
button:focus-visible {
    outline: 2px solid var(--accent-secondary);
    outline-offset: 2px;
}

.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--accent-secondary);
    color: white;
    padding: 8px 16px;
    z-index: 1000;
    transition: top 0.3s;
}

.skip-link:focus {
    top: 0;
}

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

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

    html {
        scroll-behavior: auto;
    }

    #particle-canvas {
        display: none;
    }

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

    .nav-links {
        transition: none;
    }
}

/* ============================================
   Search Component
   ============================================ */
.search-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(12px);
    z-index: 200;
    display: none;
    align-items: flex-start;
    justify-content: center;
    padding-top: 100px;
}

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

.search-container {
    width: 100%;
    max-width: 600px;
    padding: 0 20px;
}

.search-input {
    width: 100%;
    background: white;
    border: 2px solid var(--border-default);
    border-radius: var(--border-radius);
    padding: 18px 22px;
    font-size: 1.1rem;
    color: var(--text-primary);
    font-family: var(--font-sans);
}

.search-input:focus {
    outline: none;
    border-color: var(--accent-secondary);
    box-shadow: 0 0 0 4px var(--accent-secondary-100);
}

.search-close {
    position: absolute;
    top: 20px;
    right: 20px;
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 2rem;
    cursor: pointer;
    padding: 10px;
}

.search-results {
    margin-top: 20px;
    max-height: 60vh;
    overflow-y: auto;
}

.search-result-item {
    padding: 14px;
    background: white;
    border: 1px solid var(--border-default);
    border-radius: var(--border-radius-sm);
    margin-bottom: 8px;
    transition: all var(--transition-fast);
}

.search-result-item:hover {
    border-color: var(--accent-secondary);
}

.search-result-title {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.search-result-desc {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* ============================================
   Search: Type Badge & Empty State
   ============================================ */
.search-result-type {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    padding: 2px 7px;
    border-radius: var(--border-radius-sm);
    margin-bottom: 6px;
}

.search-result-type.type-skill {
    background: rgba(37, 99, 235, 0.1);
    color: var(--accent-secondary);
}

.search-result-type.type-paper {
    background: rgba(5, 150, 105, 0.1);
    color: var(--success);
}

.search-result-type.type-resource {
    background: rgba(217, 119, 6, 0.1);
    color: var(--warning);
}

.search-empty {
    text-align: center;
    padding: var(--space-xl);
    color: var(--text-tertiary);
    font-size: 0.95rem;
}

.search-hint {
    text-align: center;
    color: var(--text-tertiary);
    font-size: 0.85rem;
    margin-top: var(--space-md);
}

/* ============================================
   Hero: Entrance Animation Sequence
   ============================================ */
@keyframes heroFadeUp {
    from {
        opacity: 0;
        transform: translateY(24px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes heroFadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

.hero-content .hero-badge {
    animation: heroFadeUp 0.6s var(--ease-out) var(--hero-delay-1) both;
}

.hero-content .hero-title {
    animation: heroFadeUp 0.7s var(--ease-out) var(--hero-delay-2) both;
}

.hero-content .hero-description {
    animation: heroFadeUp 0.6s var(--ease-out) var(--hero-delay-3) both;
}

.hero-content .hero-actions {
    animation: heroFadeUp 0.6s var(--ease-out) var(--hero-delay-4) both;
}

.hero-content .hero-stats {
    animation: heroFadeUp 0.6s var(--ease-out) var(--hero-delay-5) both;
}

.hero-visual {
    animation: heroFadeIn 0.9s var(--ease-out) var(--hero-delay-6) both;
}

/* ============================================
   Hero: Enhanced Background Float
   ============================================ */
.hero::before {
    animation: gentleFloat 20s ease-in-out infinite;
}

@keyframes gentleFloat {

    0%,
    100% {
        transform: translate(0, 0) scale(1);
        opacity: 1;
    }

    25% {
        transform: translate(2%, -2%) scale(1.02);
        opacity: 0.85;
    }

    50% {
        transform: translate(-1.5%, 1.5%) scale(0.98);
        opacity: 1;
    }

    75% {
        transform: translate(1%, -1%) scale(1.01);
        opacity: 0.9;
    }
}

/* ============================================
   Typewriter Animation for Code Preview
   ============================================ */
@keyframes blink-caret {

    0%,
    100% {
        opacity: 1;
    }

    50% {
        opacity: 0;
    }
}

.typewriter-cursor {
    display: inline-block;
    width: 2px;
    height: 1em;
    background: #7f5af0;
    margin-left: 2px;
    vertical-align: text-bottom;
    animation: blink-caret 1s step-end infinite;
}

/* ============================================
   Enhanced Card Hover Effects
   ============================================ */
.skill-card:hover .skill-icon {
    transform: scale(1.15);
    transition: transform 0.25s var(--ease-spring);
}

.skill-icon {
    transition: transform 0.25s var(--ease-spring);
    display: inline-block;
    font-size: 2.25rem;
}

/* Paper card variant */
.paper-card:hover {
    border-left-color: var(--success);
}

/* Resource card variant */
.resource-card:hover {
    border-left-color: var(--warning);
}

/* ============================================
   Enhanced Navigation Scroll Effect
   ============================================ */
.nav.scrolled {
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    box-shadow: 0 1px 0 rgba(0, 0, 0, 0.08), 0 4px 12px rgba(0, 0, 0, 0.04);
    border-bottom-color: var(--border-default);
}

/* ============================================
   Section Spacing Improvements
   ============================================ */
.section+.section {
    padding-top: var(--space-2xl);
}

#skills {
    padding-top: var(--space-3xl);
}

/* ============================================
   Skill Stage Color Accents (Filter Tags)
   ============================================ */
.filter-tab[data-filter="discovery"]:hover,
.filter-tab[data-filter="discovery"].active {
    background: var(--accent-primary);
    border-color: var(--accent-primary);
    color: white;
}

.filter-tab[data-filter="data"]:hover,
.filter-tab[data-filter="data"].active {
    background: var(--success);
    border-color: var(--success);
    color: white;
}

.filter-tab[data-filter="analysis"]:hover,
.filter-tab[data-filter="analysis"].active {
    background: var(--info);
    border-color: var(--info);
    color: white;
}

.filter-tab[data-filter="communication"]:hover,
.filter-tab[data-filter="communication"].active {
    background: var(--warning);
    border-color: var(--warning);
    color: white;
}

/* ============================================
   Breadcrumb Navigation (Detail Pages)
   ============================================ */
.breadcrumb {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.85rem;
    color: var(--text-tertiary);
    margin-bottom: var(--space-lg);
    flex-wrap: wrap;
}

.breadcrumb a {
    color: var(--text-tertiary);
    transition: color var(--transition-fast);
}

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

.breadcrumb-sep {
    color: var(--border-strong);
    font-size: 0.75rem;
}

.breadcrumb-current {
    color: var(--text-secondary);
    font-weight: 500;
}

/* ============================================
   "New" Badge for Recent Items
   ============================================ */
.badge-new {
    display: inline-block;
    background: linear-gradient(135deg, var(--accent-secondary), var(--accent-primary));
    color: white;
    font-size: 0.65rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 2px 7px;
    border-radius: var(--border-radius-full);
    position: absolute;
    top: var(--space-md);
    right: var(--space-md);
}

/* ============================================
   Stats Enhancement
   ============================================ */
.hero-stats {
    gap: var(--space-2xl);
    padding-top: var(--space-md);
    border-top: 1px solid var(--border-subtle);
    margin-top: var(--space-md);
}

.stat-value {
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* ============================================
   Improved Tag Styles (Semantic Colors)
   ============================================ */
.tag[data-type="analysis"],
.tag[data-type="nlp"] {
    background: rgba(8, 145, 178, 0.08);
    color: #0891B2;
    border-color: rgba(8, 145, 178, 0.2);
}

.tag[data-type="writing"],
.tag[data-type="communication"] {
    background: rgba(217, 119, 6, 0.08);
    color: var(--warning);
    border-color: rgba(217, 119, 6, 0.2);
}

.tag[data-type="data"],
.tag[data-type="dataset"] {
    background: rgba(5, 150, 105, 0.08);
    color: var(--success);
    border-color: rgba(5, 150, 105, 0.2);
}

/* ============================================
   Taxonomy Section: Improved Visual
   ============================================ */
.taxonomy-section {
    background: linear-gradient(180deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
    border-top: 1px solid var(--border-subtle);
    border-bottom: 1px solid var(--border-subtle);
}

.taxonomy-card {
    border-top: 3px solid transparent;
}

.taxonomy-card:nth-child(1) {
    border-top-color: var(--accent-secondary);
}

.taxonomy-card:nth-child(2) {
    border-top-color: var(--success);
}

.taxonomy-card:nth-child(3) {
    border-top-color: var(--warning);
}

/* ============================================
   About Page: Fix Hardcoded Purple Color
   ============================================ */
.about-card:hover {
    transform: translateY(-4px);
    border-color: var(--accent-secondary-200);
    box-shadow: 0 20px 40px rgba(37, 99, 235, 0.1);
}

/* ============================================
   Learn Page Enhancements
   ============================================ */
.learn-page {
    padding: calc(80px + var(--space-3xl)) 0 var(--space-3xl);
}

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

.learn-header h1 {
    font-family: var(--font-heading);
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 800;
    margin: var(--space-md) 0;
    letter-spacing: -0.03em;
}

.learn-header p {
    font-size: 1.15rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
    line-height: 1.7;
}

.learn-section {
    max-width: 800px;
    margin: 0 auto var(--space-2xl);
    background: white;
    border: 1px solid var(--border-default);
    border-radius: var(--border-radius);
    padding: var(--space-xl);
    box-shadow: var(--shadow-sm);
}

.learn-section h2 {
    font-family: var(--font-heading);
    font-size: 1.4rem;
    font-weight: 700;
    margin-bottom: var(--space-md);
    color: var(--text-primary);
}

.learn-section p {
    color: var(--text-secondary);
    line-height: 1.75;
    margin-bottom: var(--space-md);
}

.learn-section ul {
    list-style: none;
    padding: 0;
}

.learn-section ul li {
    padding: var(--space-xs) 0;
    padding-left: var(--space-lg);
    position: relative;
    color: var(--text-secondary);
    line-height: 1.65;
}

.learn-section ul li::before {
    content: "→";
    position: absolute;
    left: 0;
    color: var(--accent-secondary);
    font-weight: 700;
}

.learn-code-block {
    background: var(--gray-900);
    border-radius: var(--border-radius-sm);
    padding: var(--space-md);
    margin-top: var(--space-md);
    overflow-x: auto;
}

.learn-code-block code {
    color: #e0e0e0;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    white-space: pre;
    line-height: 1.7;
    display: block;
}

.learn-code-block .comment {
    color: var(--gray-500);
}

/* ============================================
   Quick Start: Step Connector Line
   ============================================ */
.steps {
    position: relative;
}

.step {
    position: relative;
}

.step:not(:last-child) .step-number::after {
    content: "";
    position: absolute;
    top: 48px;
    left: 23px;
    width: 2px;
    height: calc(100% + var(--space-2xl) - 48px);
    background: linear-gradient(to bottom, var(--accent-secondary), transparent);
    opacity: 0.2;
}

/* ============================================
   Mobile Search Button Styling
   ============================================ */
.nav-search-btn {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    border-radius: var(--border-radius-sm);
    transition: background var(--transition-fast);
    color: var(--text-secondary);
}

.nav-search-btn:hover {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

/* ============================================
   Scroll to Top Button
   ============================================ */
#scroll-top-btn {
    position: fixed;
    bottom: var(--space-xl);
    right: var(--space-xl);
    width: 42px;
    height: 42px;
    background: var(--accent-primary);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    box-shadow: var(--shadow-lg);
    transition: all var(--transition-base);
    opacity: 0;
    transform: translateY(12px);
    pointer-events: none;
    z-index: 90;
}

#scroll-top-btn.visible {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}

#scroll-top-btn:hover {
    background: var(--accent-secondary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

/* ============================================
   Hero Code Preview: Glow Effect
   ============================================ */
.code-preview {
    box-shadow: var(--shadow-xl), 0 0 40px rgba(37, 99, 235, 0.08);
    transition: box-shadow 0.4s ease;
}

.code-preview:hover {
    box-shadow: var(--shadow-xl), 0 0 60px rgba(37, 99, 235, 0.15);
}

/* ============================================
   Filter Count Badge
   ============================================ */
.filter-count {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 18px;
    height: 18px;
    background: rgba(255, 255, 255, 0.3);
    border-radius: var(--border-radius-full);
    font-size: 0.7rem;
    font-weight: 700;
    padding: 0 4px;
    margin-left: 4px;
}

.filter-tab.active .filter-count {
    background: rgba(255, 255, 255, 0.25);
}

/* ============================================
   Smooth height transition for grid filter
   ============================================ */
.skills-grid {
    transition: opacity 0.2s ease;
}

.skills-grid.filtering {
    opacity: 0.7;
}

/* ============================================
   Dark Mode Theme
   ============================================ */
[data-theme="dark"] {
    /* Surfaces */
    --bg-primary: #0F1117;
    --bg-secondary: #161B27;
    --bg-tertiary: #1E2535;
    --bg-elevated: #1A2032;
    --bg-gradient: linear-gradient(180deg, #0F1117 0%, #161B27 100%);

    /* Text */
    --text-primary: #F1F5F9;
    --text-secondary: #94A3B8;
    --text-tertiary: #64748B;
    --text-inverse: #111827;
    --text-muted: #64748B;

    /* Accent (keep blue, lighten slightly for dark bg) */
    --accent-primary: #E2E8F0;
    --accent-primary-light: #F1F5F9;
    --accent-primary-dark: #CBD5E1;
    --accent-primary-50: rgba(226, 232, 240, 0.05);
    --accent-primary-100: rgba(226, 232, 240, 0.1);
    --accent-secondary: #3B82F6;
    --accent-secondary-light: #60A5FA;
    --accent-secondary-100: rgba(59, 130, 246, 0.15);
    --accent-secondary-200: rgba(59, 130, 246, 0.25);
    --accent-gradient: linear-gradient(135deg, #F1F5F9 0%, #3B82F6 100%);

    /* Borders */
    --border-subtle: rgba(255, 255, 255, 0.05);
    --border-default: rgba(255, 255, 255, 0.08);
    --border-strong: rgba(255, 255, 255, 0.15);
    --border-color: rgba(255, 255, 255, 0.08);
    --border-accent: rgba(59, 130, 246, 0.5);

    /* Glass */
    --glass-bg: rgba(22, 27, 39, 0.85);
    --glass-border: rgba(255, 255, 255, 0.08);
    --glass-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);

    /* Shadows (more prominent on dark) */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.5);
    --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.6);

    /* Grays (inverted scale for dark) */
    --gray-50: #0F1117;
    --gray-100: #161B27;
    --gray-200: #1E2535;
    --gray-800: #D1D5DB;
    --gray-900: #0A0D14;
}

/* Dark mode: body background */
[data-theme="dark"] body {
    background: var(--bg-gradient);
    color: var(--text-primary);
}

/* Dark mode: navigation */
[data-theme="dark"] .nav {
    background: rgba(15, 17, 23, 0.92);
    border-bottom-color: var(--border-default);
}

[data-theme="dark"] .nav.scrolled {
    background: rgba(15, 17, 23, 0.98);
    box-shadow: 0 1px 0 rgba(255, 255, 255, 0.06), 0 4px 12px rgba(0, 0, 0, 0.3);
}

/* Dark mode: cards */
[data-theme="dark"] .skill-card,
[data-theme="dark"] .taxonomy-card,
[data-theme="dark"] .tool-comp-card,
[data-theme="dark"] .stage-card,
[data-theme="dark"] .feature-item,
[data-theme="dark"] .about-card {
    background: var(--bg-elevated);
    border-color: var(--border-default);
}

[data-theme="dark"] .skill-card:hover,
[data-theme="dark"] .taxonomy-card:hover {
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.4), 0 0 0 1px var(--accent-secondary-200);
}

/* Dark mode: sections */
[data-theme="dark"] .quickstart-section,
[data-theme="dark"] .taxonomy-section,
[data-theme="dark"] .author-section,
[data-theme="dark"] .footer {
    background: var(--bg-secondary);
    border-color: var(--border-default);
}

/* Dark mode: code blocks */
[data-theme="dark"] .code-block,
[data-theme="dark"] .learn-code,
[data-theme="dark"] .learn-code-block {
    background: #0A0D14;
    border-color: rgba(255, 255, 255, 0.08);
}

/* Dark mode: form inputs */
[data-theme="dark"] input[type="text"],
[data-theme="dark"] input[type="email"],
[data-theme="dark"] input[type="url"],
[data-theme="dark"] input[type="number"],
[data-theme="dark"] select,
[data-theme="dark"] textarea {
    background: var(--bg-tertiary);
    border-color: var(--border-default);
    color: var(--text-primary);
}

[data-theme="dark"] input:focus,
[data-theme="dark"] select:focus,
[data-theme="dark"] textarea:focus {
    border-color: var(--accent-secondary);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

/* Dark mode: form container */
[data-theme="dark"] .form-container {
    background: rgba(22, 27, 39, 0.9);
    border-color: var(--border-default);
}

/* Dark mode: search overlay */
[data-theme="dark"] .search-overlay {
    background: rgba(15, 17, 23, 0.97);
}

[data-theme="dark"] .search-input {
    background: var(--bg-elevated);
    border-color: var(--border-default);
    color: var(--text-primary);
}

[data-theme="dark"] .search-result-item {
    background: var(--bg-elevated);
    border-color: var(--border-default);
}

[data-theme="dark"] .search-result-title {
    color: var(--text-primary);
}

/* Dark mode: tool cards, filter tabs */
[data-theme="dark"] .tool-card,
[data-theme="dark"] .filter-tab {
    background: var(--bg-elevated);
    border-color: var(--border-default);
    color: var(--text-secondary);
}

[data-theme="dark"] .filter-tab:hover {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

[data-theme="dark"] .filter-tab.active {
    background: var(--accent-secondary);
    border-color: var(--accent-secondary);
    color: white;
}

/* Dark mode: nav lang tag */
[data-theme="dark"] .nav-lang {
    background: var(--bg-tertiary);
    border-color: var(--border-default);
    color: var(--text-secondary);
}

/* Dark mode: buttons */
[data-theme="dark"] .btn-secondary {
    background: var(--bg-elevated);
    border-color: var(--border-default);
    color: var(--text-primary);
}

[data-theme="dark"] .btn-secondary:hover {
    background: var(--bg-tertiary);
    border-color: var(--accent-secondary);
    color: var(--accent-secondary);
}

/* Dark mode: learn page section cards */
[data-theme="dark"] .learn-section-card {
    background: var(--bg-elevated);
    border-color: var(--border-default);
}

/* Dark mode: tags */
[data-theme="dark"] .tag {
    background: var(--bg-tertiary);
    border-color: var(--border-default);
    color: var(--text-secondary);
}

/* Dark mode: mobile nav menu */
[data-theme="dark"] .nav-links {
    background: rgba(15, 17, 23, 0.98);
}

/* ============================================
   Dark Mode Toggle Button
   ============================================ */
#dark-mode-toggle {
    background: none;
    border: 1px solid var(--border-default);
    border-radius: var(--border-radius-sm);
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 0.95rem;
    color: var(--text-secondary);
    transition: all var(--transition-fast);
    flex-shrink: 0;
}

#dark-mode-toggle:hover {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border-color: var(--border-strong);
}

[data-theme="dark"] #dark-mode-toggle {
    border-color: var(--border-default);
    color: var(--text-secondary);
}

[data-theme="dark"] #dark-mode-toggle:hover {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}