/* ============================================
   Elementary Charge - Light Theme Design
   ============================================ */

/* CSS Variables */
:root {
    /* Colors - Light Theme */
    --color-bg: #f8fafc;
    --color-bg-alt: #ffffff;
    --color-bg-card: #ffffff;
    --color-text: #1e293b;
    --color-text-secondary: #64748b;
    --color-text-muted: #94a3b8;

    /* Primary - Deep Blue */
    --color-primary: #2563eb;
    --color-primary-light: #3b82f6;
    --color-primary-dark: #1d4ed8;
    --color-primary-bg: #eff6ff;

    /* Accent - Electric Purple */
    --color-accent: #7c3aed;
    --color-accent-light: #8b5cf6;

    /* Semantic Colors */
    --color-positive: #10b981;
    --color-negative: #ef4444;
    --color-warning: #f59e0b;
    --color-info: #0ea5e9;

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #2563eb 0%, #7c3aed 100%);
    --gradient-hero: linear-gradient(180deg, rgba(248, 250, 252, 0.8) 0%, rgba(224, 242, 254, 0.8) 50%, rgba(248, 250, 252, 0.8) 100%);
    --gradient-card: linear-gradient(135deg, rgba(255, 255, 255, 0.9) 0%, rgba(248, 250, 252, 0.9) 100%);

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --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);
    --shadow-glow: 0 0 40px rgba(37, 99, 235, 0.15);

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

    /* Spacing */
    --section-padding: 6rem;
    --container-width: 1200px;

    /* Borders */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 400ms cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-sans);
    color: var(--color-text);
    background-color: var(--color-bg);
    line-height: 1.7;
    overflow-x: hidden;
}

/* Particle Canvas Background */
#particle-canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: -1;
    opacity: 0.6;
}

/* Container */
.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 2rem;
}

/* Typography */
h1,
h2,
h3,
h4,
h5,
h6 {
    font-weight: 600;
    line-height: 1.3;
    color: var(--color-text);
}

h1 {
    font-size: 3.5rem;
}

h2 {
    font-size: 2.5rem;
}

h3 {
    font-size: 1.75rem;
}

h4 {
    font-size: 1.25rem;
}

p {
    margin-bottom: 1rem;
}

.lead {
    font-size: 1.25rem;
    color: var(--color-text-secondary);
    margin-bottom: 1.5rem;
}

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

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

code {
    font-family: var(--font-mono);
    font-size: 0.9em;
    background: var(--color-primary-bg);
    padding: 0.2em 0.4em;
    border-radius: var(--radius-sm);
    color: var(--color-primary-dark);
}

strong {
    font-weight: 600;
    color: var(--color-text);
}

/* ============================================
   Navigation
   ============================================ */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    transition: all var(--transition-base);
}

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

.nav-container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0.75rem 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    display: flex;
    align-items: baseline;
    gap: 0.5rem;
    font-weight: 600;
    color: var(--color-text);
    text-decoration: none;
}

.logo-e {
    font-size: 1.75rem;
    font-style: italic;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.logo-value {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--color-text-secondary);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-menu a {
    color: var(--color-text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
    transition: color var(--transition-fast);
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient-primary);
    transition: width var(--transition-base);
}

.nav-menu a:hover {
    color: var(--color-primary);
}

.nav-menu a:hover::after {
    width: 100%;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

/* Language Selector */
.language-selector {
    position: relative;
}

.lang-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: var(--color-bg);
    border: 1px solid rgba(0, 0, 0, 0.1);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    transition: all var(--transition-fast);
}

.lang-btn:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
}

.lang-dropdown {
    position: absolute;
    top: 100%;
    right: 0;
    margin-top: 0.5rem;
    background: var(--color-bg-card);
    border: 1px solid rgba(0, 0, 0, 0.1);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    list-style: none;
    min-width: 150px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-fast);
}

.lang-dropdown.active {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.lang-dropdown li {
    padding: 0.75rem 1rem;
    cursor: pointer;
    font-size: 0.875rem;
    transition: background var(--transition-fast);
}

.lang-dropdown li:hover {
    background: var(--color-primary-bg);
}

.lang-dropdown li.active {
    color: var(--color-primary);
    font-weight: 500;
}

/* More Dropdown (for Desktop Overflow) */
.nav-item-more {
    position: relative;
}

.nav-more-dropdown {
    position: absolute;
    top: 100%;
    right: 0;
    margin-top: 0.5rem;
    background: var(--color-bg-card);
    border: 1px solid rgba(0, 0, 0, 0.1);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    list-style: none;
    min-width: 200px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-fast);
    padding: 0.5rem 0;
}

.nav-item-more:hover .nav-more-dropdown,
.nav-item-more:focus-within .nav-more-dropdown {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.nav-more-dropdown li {
    display: block;
}

.nav-more-dropdown a {
    display: block;
    padding: 0.75rem 1.5rem;
    color: var(--color-text-secondary);
    transition: all var(--transition-fast);
    font-size: 0.9rem;
}

.nav-more-dropdown a:hover {
    background: var(--color-primary-bg);
    color: var(--color-primary);
}

/* Remove hover line for dropdown items */
.nav-more-dropdown a::after {
    display: none;
}

/* Mobile Menu Button */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 0.5rem;
    background: none;
    border: none;
    cursor: pointer;
}

.mobile-menu-btn span {
    width: 24px;
    height: 2px;
    background: var(--color-text);
    transition: all var(--transition-fast);
}

/* ============================================
   Hero Section
   ============================================ */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 8rem 2rem 4rem;
    background: var(--gradient-hero);
    position: relative;
    overflow: hidden;
}

.hero-content {
    width: 100%;
    max-width: 1400px;
    text-align: center;
    z-index: 2;
    /* Moved on top of visual */
}

.hero-badge {
    display: inline-block;
    padding: 0.5rem 1.25rem;
    background: var(--color-primary-bg);
    color: var(--color-primary);
    font-size: 0.875rem;
    font-weight: 600;
    border-radius: 2rem;
    margin-bottom: 1.5rem;
    animation: fadeInDown 0.8s ease-out;
}

.hero-title {
    margin-bottom: 1.5rem;
    animation: fadeInUp 0.8s ease-out 0.2s both;
}

.hero-label {
    display: block;
    font-size: 1.5rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    margin-bottom: 0.5rem;
    letter-spacing: 0.05em;
}

.hero-value {
    display: flex;
    align-items: baseline;
    justify-content: center;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.value-e {
    font-size: 5rem;
    font-style: italic;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.value-equals {
    font-size: 3rem;
    color: var(--color-text-muted);
}

.value-number {
    font-family: var(--font-mono);
    font-size: 3rem;
    font-weight: 500;
    color: var(--color-text);
}

.value-exp {
    font-family: var(--font-mono);
    font-size: 2rem;
    color: var(--color-text-secondary);
}

.value-unit {
    font-size: 2.5rem;
    font-weight: 500;
    color: var(--color-primary);
}

.hero-description {
    font-size: 1.25rem;
    color: var(--color-text-secondary);
    max-width: 600px;
    margin: 0 auto 2rem;
    animation: fadeInUp 0.8s ease-out 0.4s both;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 3rem;
    animation: fadeInUp 0.8s ease-out 0.6s both;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 2rem;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-base);
    text-decoration: none;
    border: none;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: 0 4px 15px rgba(37, 99, 235, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(37, 99, 235, 0.4);
    color: white;
}

.btn-secondary {
    background: var(--color-bg-card);
    color: var(--color-text);
    border: 1px solid rgba(0, 0, 0, 0.1);
}

.btn-secondary:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 3rem;
    animation: fadeInUp 0.8s ease-out 0.8s both;
}

.stat {
    text-align: center;
}

.stat-value {
    display: block;
    font-size: 2rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: 0.25rem;
}

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

/* Hero Visual - Atom Animation */
.hero-visual {
    position: absolute;
    right: 5%;
    top: 50%;
    transform: translateY(-50%);
    opacity: 0.6;
    /* Increased visibility */
    z-index: 0;
}

.atom-visualization {
    width: 400px;
    height: 400px;
    position: relative;
}

.nucleus {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

.proton {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--color-positive) 0%, #059669 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: white;
    font-weight: 700;
    box-shadow: 0 0 30px rgba(16, 185, 129, 0.5);
    animation: pulse 2s ease-in-out infinite;
}

.electron-orbit {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: 2px dashed rgba(37, 99, 235, 0.3);
    border-radius: 50%;
    animation: rotate 8s linear infinite;
}

.electron {
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%) translateY(-50%);
    width: 24px;
    height: 24px;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 700;
    font-size: 1.25rem;
    box-shadow: 0 0 20px rgba(37, 99, 235, 0.5);
}

/* Scroll Indicator */
.scroll-indicator {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    color: var(--color-text-muted);
    font-size: 0.875rem;
    animation: fadeIn 1s ease-out 1.2s both;
}

.scroll-arrow {
    width: 24px;
    height: 24px;
    border-right: 2px solid var(--color-primary);
    border-bottom: 2px solid var(--color-primary);
    transform: rotate(45deg);
    animation: bounce 2s ease-in-out infinite;
}

/* ============================================
   Sections
   ============================================ */
.section {
    padding: var(--section-padding) 0;
    position: relative;
}

.section-alt {
    background: var(--color-bg-alt);
}

.section-header {
    margin-bottom: 3rem;
}

.section-number {
    display: block;
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--color-primary);
    margin-bottom: 0.5rem;
    letter-spacing: 0.1em;
}

.section-title {
    font-size: 2.5rem;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -0.5rem;
    left: 0;
    width: 60px;
    height: 4px;
    background: var(--gradient-primary);
    border-radius: 2px;
}

/* Content Grid */
.content-grid {
    display: grid;
    grid-template-columns: 1fr 320px;
    gap: 3rem;
    align-items: start;
}

.content-main h3 {
    margin-top: 2rem;
    margin-bottom: 1rem;
    color: var(--color-text);
}

.content-main h4 {
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
}

/* Sidebar */
.content-sidebar {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    position: sticky;
    top: 100px;
}

.sidebar-card {
    background: var(--color-bg-card);
    border: 1px solid rgba(0, 0, 0, 0.05);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-sm);
}

.sidebar-card h4 {
    font-size: 1rem;
    margin-bottom: 1rem;
    color: var(--color-text);
}

.fact-list {
    list-style: none;
}

.fact-list li {
    padding: 0.5rem 0;
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.fact-list li:last-child {
    border-bottom: none;
}

/* Info Box */
.info-box {
    display: flex;
    gap: 1rem;
    padding: 1.25rem;
    background: var(--color-primary-bg);
    border-radius: var(--radius-lg);
    margin: 1.5rem 0;
    border-left: 4px solid var(--color-primary);
}

.info-box.warning {
    background: #fef3c7;
    border-left-color: var(--color-warning);
}

.info-icon {
    font-size: 1.5rem;
    line-height: 1;
}

.info-content h4 {
    margin-bottom: 0.5rem;
    font-size: 1rem;
}

.info-content p {
    font-size: 0.9rem;
    margin-bottom: 0;
}

/* Data Table */
.table-responsive {
    overflow-x: auto;
    margin: 1.5rem 0;
}

.data-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.9rem;
}

.data-table th,
.data-table td {
    padding: 0.875rem 1rem;
    text-align: left;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.data-table th {
    background: var(--color-bg);
    font-weight: 600;
    color: var(--color-text);
}

.data-table tr:hover td {
    background: var(--color-primary-bg);
}

/* Video Embed */
.video-card {
    padding: 1rem;
}

.video-embed {
    position: relative;
    border-radius: var(--radius-md);
    overflow: hidden;
    background: #000;
    width: 100%;
    padding-bottom: 56.25%;
    /* 16:9 Aspect Ratio */
    height: 0;
}

.video-embed iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: 0;
}

.video-caption {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    margin-top: 0.75rem;
    text-align: center;
}



.video-caption {
    font-size: 0.8rem;
    color: var(--color-text-muted);
    margin-top: 0.75rem;
    text-align: center;
}

/* Card Grid */
.card-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
    margin: 1.5rem 0;
}

.unit-card {
    background: var(--color-bg-card);
    border: 1px solid rgba(0, 0, 0, 0.05);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    transition: all var(--transition-base);
}

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

.unit-card h4 {
    color: var(--color-primary);
    margin-bottom: 0.5rem;
    font-size: 1rem;
}

.unit-card p {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    margin-bottom: 0;
}

/* Formula Box */
.formula-box {
    background: var(--color-bg-card);
    border: 1px solid rgba(0, 0, 0, 0.05);
    border-radius: var(--radius-lg);
    padding: 2rem;
    margin: 1.5rem 0;
    text-align: center;
}

.formula-box.compact {
    padding: 1rem;
}

.formula-box.highlight {
    background: var(--color-primary-bg);
    border-color: var(--color-primary);
}

.formula {
    font-family: var(--font-mono);
    font-size: 1.5rem;
    color: var(--color-text);
}

.formula .fraction {
    display: inline-flex;
    flex-direction: column;
    vertical-align: middle;
    text-align: center;
}

.formula .numerator {
    border-bottom: 2px solid var(--color-text);
    padding-bottom: 0.25rem;
}

.formula .denominator {
    padding-top: 0.25rem;
}

.formula-caption {
    font-size: 0.875rem;
    color: var(--color-text-muted);
    margin-top: 0.75rem;
}

.formula-list {
    text-align: left;
}

.formula-item {
    padding: 0.75rem 0;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

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

.formula-label {
    display: block;
    font-size: 0.8rem;
    color: var(--color-text-muted);
    margin-bottom: 0.25rem;
}

.formula-item code {
    font-size: 0.85rem;
}

/* Highlight Box */
.highlight-box {
    background: linear-gradient(135deg, var(--color-primary-bg) 0%, #faf5ff 100%);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    margin: 1.5rem 0;
}

.highlight-box h4 {
    color: var(--color-primary);
    margin-bottom: 1rem;
}

.highlight-box ul {
    list-style: none;
    margin: 0;
}

.highlight-box li {
    padding: 0.5rem 0;
    padding-left: 1.5rem;
    position: relative;
    font-size: 0.9rem;
    color: var(--color-text-secondary);
}

.highlight-box li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--color-accent);
}

/* ============================================
   Quantization Section
   ============================================ */
.subsection {
    margin-bottom: 4rem;
}

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

.quark-section {
    background: var(--color-bg-card);
    border-radius: var(--radius-lg);
    padding: 2rem;
    margin: 1.5rem 0;
    border: 1px solid rgba(0, 0, 0, 0.05);
}

.quark-table {
    margin: 1.5rem 0;
}

.quark-row {
    display: grid;
    grid-template-columns: 1fr auto;
    padding: 0.875rem 1rem;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    align-items: center;
}

.quark-row.header {
    font-weight: 600;
    background: var(--color-bg);
    border-radius: var(--radius-md) var(--radius-md) 0 0;
}

.charge {
    font-family: var(--font-mono);
    font-weight: 600;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-sm);
}

.charge.positive {
    background: rgba(16, 185, 129, 0.1);
    color: var(--color-positive);
}

.charge.negative {
    background: rgba(239, 68, 68, 0.1);
    color: var(--color-negative);
}

.proton-composition {
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 1px solid rgba(0, 0, 0, 0.05);
}

.proton-composition h5 {
    margin-bottom: 1rem;
    font-size: 1rem;
}

.particle-diagram {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    flex-wrap: wrap;
    margin: 1.5rem 0;
}

.quark {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 700;
}

.quark span {
    font-size: 0.65rem;
    opacity: 0.9;
}

.quark.up {
    background: linear-gradient(135deg, #3b82f6 0%, #2563eb 100%);
}

.quark.down {
    background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
}

.plus,
.equals {
    font-size: 1.5rem;
    color: var(--color-text-muted);
}

.result {
    font-family: var(--font-mono);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-positive);
    padding: 0.5rem 1rem;
    background: rgba(16, 185, 129, 0.1);
    border-radius: var(--radius-md);
}

.diagram-caption {
    font-size: 0.875rem;
    color: var(--color-text-muted);
    text-align: center;
}

/* Award Box */
.award-box {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.25rem;
    background: linear-gradient(135deg, #fef3c7 0%, #fde68a 100%);
    border-radius: var(--radius-lg);
    margin: 1rem 0;
}

.award-box.compact {
    padding: 0.75rem 1rem;
}

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

.award-content h4 {
    margin-bottom: 0.25rem;
    font-size: 0.95rem;
}

.award-content p,
.award-box.compact p {
    margin-bottom: 0;
    font-size: 0.875rem;
    color: #92400e;
}

/* ============================================
   Experiments Section
   ============================================ */
.experiment-card {
    background: var(--color-bg-card);
    border: 1px solid rgba(0, 0, 0, 0.05);
    border-radius: var(--radius-xl);
    padding: 2rem;
    margin-bottom: 2rem;
    transition: all var(--transition-base);
}

.experiment-card:hover {
    box-shadow: var(--shadow-lg);
}

.experiment-card.featured {
    background: linear-gradient(135deg, var(--color-bg-card) 0%, var(--color-primary-bg) 100%);
    border-color: var(--color-primary);
}

.experiment-card.highlight {
    background: linear-gradient(135deg, var(--color-primary-bg) 0%, #dbeafe 100%);
    border-color: var(--color-primary);
}

.experiment-header {
    margin-bottom: 1.5rem;
}

.experiment-year {
    display: inline-block;
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--color-primary);
    background: var(--color-primary-bg);
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    margin-bottom: 0.5rem;
}

.experiment-header h3 {
    font-size: 1.5rem;
}

.experiment-content {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 2rem;
}

.experiment-card:not(.featured) .experiment-content {
    display: block;
}

.process-list {
    margin: 1rem 0 1.5rem;
    padding-left: 0;
    list-style: none;
    counter-reset: step;
}

.process-list li {
    counter-increment: step;
    padding: 0.75rem 0;
    padding-left: 3rem;
    position: relative;
    border-left: 2px solid var(--color-primary-bg);
}

.process-list li::before {
    content: counter(step);
    position: absolute;
    left: -11px;
    top: 0.75rem;
    width: 22px;
    height: 22px;
    background: var(--color-primary);
    color: white;
    border-radius: 50%;
    font-size: 0.75rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
}

.experiment-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
    margin-top: 2rem;
}

.formula-relationship {
    margin-top: 3rem;
    text-align: center;
    padding: 2rem;
    background: var(--color-bg-card);
    border-radius: var(--radius-xl);
    border: 1px solid rgba(0, 0, 0, 0.05);
}

.formula-relationship h4 {
    margin-bottom: 1rem;
}

.formula-relationship p {
    max-width: 600px;
    margin: 1rem auto 0;
    font-size: 0.9rem;
    color: var(--color-text-secondary);
}

/* ============================================
   Timeline
   ============================================ */
.timeline {
    position: relative;
    padding-left: 3rem;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 10px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: linear-gradient(180deg, var(--color-primary) 0%, var(--color-accent) 100%);
}

.timeline-item {
    position: relative;
    padding-bottom: 2.5rem;
}

.timeline-item:last-child {
    padding-bottom: 0;
}

.timeline-marker {
    position: absolute;
    left: -2.5rem;
    top: 0.25rem;
    width: 16px;
    height: 16px;
    background: var(--color-bg);
    border: 3px solid var(--color-primary);
    border-radius: 50%;
    z-index: 1;
}

.timeline-item.highlight .timeline-marker {
    background: var(--color-primary);
    box-shadow: 0 0 0 4px var(--color-primary-bg);
}

.timeline-content {
    background: var(--color-bg-card);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    border: 1px solid rgba(0, 0, 0, 0.05);
    transition: all var(--transition-base);
}

.timeline-item:hover .timeline-content {
    box-shadow: var(--shadow-md);
}

.timeline-item.highlight .timeline-content {
    background: linear-gradient(135deg, var(--color-primary-bg) 0%, #f0f9ff 100%);
    border-color: var(--color-primary);
}

.timeline-year {
    display: inline-block;
    font-family: var(--font-mono);
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: 0.5rem;
}

.timeline-content h4 {
    margin-bottom: 0.5rem;
}

.timeline-content p {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    margin-bottom: 0.75rem;
}

.timeline-content .award-box {
    margin-top: 0.75rem;
    margin-bottom: 0;
}

/* ============================================
   Applications Grid
   ============================================ */
.app-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
    margin: 2rem 0 3rem;
}

.app-card {
    background: var(--color-bg-card);
    border: 1px solid rgba(0, 0, 0, 0.05);
    border-radius: var(--radius-lg);
    padding: 2rem;
    text-align: center;
    transition: all var(--transition-base);
}

.app-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary);
}

.app-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.app-card h4 {
    color: var(--color-primary);
    margin-bottom: 0.75rem;
}

.app-card p {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    margin-bottom: 0;
}

/* ============================================
   Footer
   ============================================ */
.footer {
    background: #1e293b;
    color: #e2e8f0;
    padding: 4rem 0 2rem;
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-brand {
    max-width: 400px;
}

.footer-logo {
    font-family: var(--font-mono);
    font-size: 1.25rem;
    color: white;
    margin-bottom: 0.75rem;
    display: block;
}

.footer-brand p {
    color: #94a3b8;
    font-size: 0.9rem;
}

.footer-nav h5,
.footer-references h5,
.footer-about h5 {
    color: white;
    font-size: 0.9rem;
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.footer-nav ul,
.footer-references ul,
.footer-about ul {
    list-style: none;
}

.footer-nav li,
.footer-references li,
.footer-about li {
    margin-bottom: 0.5rem;
}

.footer-nav a,
.footer-references a,
.footer-about a {
    color: #94a3b8;
    font-size: 0.9rem;
    transition: color var(--transition-fast);
}

.footer-nav a:hover,
.footer-references a:hover,
.footer-about a:hover {
    color: white;
}

.footer-bottom {
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    text-align: center;
}

.footer-bottom p {
    color: #64748b;
    font-size: 0.875rem;
    margin-bottom: 0;
}

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

    to {
        opacity: 1;
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

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

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

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

@keyframes pulse {

    0%,
    100% {
        transform: scale(1);
        box-shadow: 0 0 30px rgba(16, 185, 129, 0.5);
    }

    50% {
        transform: scale(1.05);
        box-shadow: 0 0 50px rgba(16, 185, 129, 0.7);
    }
}

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

    to {
        transform: rotate(360deg);
    }
}

@keyframes bounce {

    0%,
    100% {
        transform: rotate(45deg) translateY(0);
    }

    50% {
        transform: rotate(45deg) translateY(10px);
    }
}

/* Scroll animations */
.animate-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease-out;
}

.animate-on-scroll.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 1024px) {
    .content-grid {
        grid-template-columns: 1fr;
    }

    .content-sidebar {
        position: static;
        flex-direction: row;
        flex-wrap: wrap;
    }

    .sidebar-card {
        flex: 1;
        min-width: 280px;
    }

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

    .experiment-content {
        grid-template-columns: 1fr;
    }

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

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

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

@media (max-width: 768px) {
    html {
        font-size: 15px;
    }

    .nav-menu {
        position: fixed;
        top: 60px;
        left: 0;
        right: 0;
        background: var(--color-bg-card);
        flex-direction: column;
        padding: 1.5rem;
        gap: 0;
        opacity: 0;
        visibility: hidden;
        transform: translateY(-10px);
        transition: all var(--transition-base);
        box-shadow: var(--shadow-lg);
    }

    .nav-menu.active {
        opacity: 1;
        visibility: visible;
        transform: translateY(0);
    }

    .nav-menu li {
        border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    }

    .nav-menu a {
        display: block;
        padding: 1rem 0;
    }

    .mobile-menu-btn {
        display: flex;
    }

    .hero {
        padding: 6rem 1.5rem 3rem;
    }

    .hero-visual {
        display: none;
    }

    .value-e {
        font-size: 3.5rem;
    }

    .value-number {
        font-size: 2rem;
    }

    .value-exp {
        font-size: 1.25rem;
    }

    .value-unit {
        font-size: 1.75rem;
    }

    .hero-stats {
        gap: 1.5rem;
    }

    .stat-value {
        font-size: 1.5rem;
    }

    .section {
        padding: 4rem 0;
    }

    .section-title {
        font-size: 2rem;
    }

    .card-grid,
    .experiment-grid,
    .app-grid {
        grid-template-columns: 1fr;
    }

    .timeline {
        padding-left: 2rem;
    }

    .timeline-marker {
        left: -1.5rem;
        width: 12px;
        height: 12px;
    }

    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .footer-brand {
        max-width: none;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }

    .hero-actions {
        flex-direction: column;
    }

    .hero-stats {
        flex-direction: column;
        gap: 1rem;
    }

    .hero-value {
        flex-direction: column;
        gap: 0.25rem;
    }

    .particle-diagram {
        flex-direction: column;
    }

    .formula {
        font-size: 1.2rem;
    }
}

/* Print Styles */
@media print {

    .navbar,
    .hero-visual,
    .scroll-indicator,
    .video-embed,
    #particle-canvas {
        display: none !important;
    }

    .hero {
        min-height: auto;
        padding: 2rem;
    }

    .section {
        padding: 2rem 0;
        break-inside: avoid;
    }

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

/* ============================================
   Books Section
   ============================================ */
.book-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.book-card {
    background: var(--color-bg-card);
    border: 1px solid rgba(0, 0, 0, 0.05);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    transition: all var(--transition-base);
}

.book-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary);
}

.book-cover {
    width: 140px;
    height: 210px;
    object-fit: cover;
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-md);
    margin-bottom: 1.5rem;
    background-color: #f0f0f0;
    /* Fallback */
}

.book-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--color-text);
    line-height: 1.4;
}

.book-author {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    margin-bottom: 0.5rem;
}

.book-publisher {
    font-size: 0.8rem;
    color: var(--color-text-tertiary);
    margin-bottom: 1rem;
    font-style: italic;
}

.book-link {
    margin-top: auto;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--color-primary);
    text-decoration: none;
    border: 1px solid var(--color-primary);
    padding: 0.5rem 1rem;
    border-radius: var(--radius-full);
    transition: all var(--transition-fast);
}

.book-link:hover {
    background: var(--color-primary);
    color: white;
}

@media (max-width: 768px) {
    .book-grid {
        grid-template-columns: 1fr;
    }
}

/* ============================================
   Related Topics Section
   ============================================ */
.related-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
    margin-top: 2rem;
}

.related-card {
    background: var(--color-bg-card);
    border: 1px solid rgba(0, 0, 0, 0.05);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    transition: all var(--transition-base);
    display: flex;
    flex-direction: column;
}

.related-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary);
}

.related-icon {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.related-card h4 {
    color: var(--color-primary);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.related-card p {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    flex-grow: 1;
    margin-bottom: 1rem;
}

.related-link {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-primary);
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    transition: gap var(--transition-fast);
}

.related-link:hover {
    gap: 0.5rem;
}

/* ============================================
   References Section
   ============================================ */
.references-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
    margin-top: 2rem;
}

.ref-category {
    background: var(--color-bg-card);
    border: 1px solid rgba(0, 0, 0, 0.05);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
}

.ref-category h4 {
    margin-bottom: 1rem;
    font-size: 1rem;
    color: var(--color-text);
}

.ref-list {
    list-style: none;
}

.ref-list li {
    padding: 0.5rem 0;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.ref-list li:last-child {
    border-bottom: none;
}

.ref-list a {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    transition: color var(--transition-fast);
}

.ref-list a:hover {
    color: var(--color-primary);
}

.citation-box {
    margin-top: 2rem;
    padding: 1.5rem;
    background: linear-gradient(135deg, var(--color-primary-bg) 0%, #f0f9ff 100%);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-primary);
}

.citation-box h4 {
    margin-bottom: 1rem;
    color: var(--color-primary);
}

.citation-content {
    background: var(--color-bg-card);
    padding: 1rem;
    border-radius: var(--radius-md);
    overflow-x: auto;
}

.citation-content code {
    font-size: 0.85rem;
    background: none;
    padding: 0;
    color: var(--color-text);
}

/* Responsive for new sections */
@media (max-width: 1024px) {
    .related-grid {
        grid-template-columns: repeat(2, 1fr);
    }

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

@media (max-width: 768px) {
    .related-grid {
        grid-template-columns: 1fr;
    }

    /* Mobile Navigation */
    .mobile-menu-btn {
        display: flex;
        z-index: 1001;
        /* Above mobile menu */
    }

    .nav-menu {
        position: fixed;
        top: 0;
        right: -100%;
        /* Hidden by default */
        width: 70%;
        height: 100vh;
        background: rgba(255, 255, 255, 0.95);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 2rem;
        transition: right var(--transition-base);
        box-shadow: -5px 0 15px rgba(0, 0, 0, 0.1);
        padding: 2rem;
        z-index: 1000;
    }

    .nav-menu.active {
        right: 0;
    }

    .nav-menu a {
        font-size: 1.25rem;
        font-weight: 600;
    }

    /* Animate hamburger to X */
    .nav-menu.active~.nav-actions .mobile-menu-btn span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .nav-menu.active~.nav-actions .mobile-menu-btn span:nth-child(2) {
        opacity: 0;
    }

    .nav-menu.active~.nav-actions .mobile-menu-btn span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }

    /* Ensure language selector stays visible and positioned */
    .nav-actions {
        z-index: 1001;
    }
}

/* ============================================
   Visual Enhancements & Parallax
   ============================================ */

/* Parallax Background */
.parallax-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    z-index: -1;
    pointer-events: none;
}

.parallax-layer {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-size: cover;
    background-position: center;
    opacity: 0.6;
    /* Increased visibility */
}

/* Abstract Shapes for Parallax */
.floating-shape {
    position: absolute;
    border-radius: 50%;
    filter: blur(60px);
    opacity: 0.4;
    z-index: -1;
    animation: float 20s infinite ease-in-out;
}

.shape-1 {
    top: 10%;
    left: 10%;
    width: 300px;
    height: 300px;
    background: radial-gradient(circle, var(--color-primary-light) 0%, transparent 70%);
    animation-delay: 0s;
}

.shape-2 {
    top: 60%;
    right: 10%;
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, var(--color-accent) 0%, transparent 70%);
    animation-delay: -5s;
}

.shape-3 {
    bottom: -10%;
    left: 30%;
    width: 250px;
    height: 250px;
    background: radial-gradient(circle, var(--color-info) 0%, transparent 70%);
    animation-delay: -10s;
}

@keyframes float {

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

    33% {
        transform: translate(30px, -50px) scale(1.1);
    }

    66% {
        transform: translate(-20px, 20px) scale(0.9);
    }
}

/* Glassmorphism Enhancements */
.sidebar-card,
.info-box,
.video-embed,
.app-card {
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.4);
    box-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.07);
}

.stat {
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    background: rgba(255, 255, 255, 0.5);
    /* Lighter background for stats */
}

.sidebar-card {
    background: rgba(255, 255, 255, 0.7);
}

.info-box {
    background: rgba(239, 246, 255, 0.8);
    /* primary-bg with opacity */
}

/* Enhanced Buttons */
.btn-primary {
    background: linear-gradient(135deg, #2563eb 0%, #6366f1 100%);
    position: relative;
    overflow: hidden;
    z-index: 1;
}

.btn-primary::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, #6366f1 0%, #2563eb 100%);
    opacity: 0;
    z-index: -1;
    transition: opacity 0.3s ease;
}

.btn-primary:hover::before {
    opacity: 1;
}

/* Scroll Reveal Animations */
.reveal-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.8s cubic-bezier(0.5, 0, 0, 1);
}

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

.reveal-left {
    opacity: 0;
    transform: translateX(-30px);
    transition: all 0.8s cubic-bezier(0.5, 0, 0, 1);
}

.reveal-left.visible {
    opacity: 1;
    transform: translateX(0);
}

.reveal-right {
    opacity: 0;
    transform: translateX(30px);
    transition: all 0.8s cubic-bezier(0.5, 0, 0, 1);
}

.reveal-right.visible {
    opacity: 1;
    transform: translateX(0);
}

/* Smooth Scrolling for entire page */
html {
    scroll-behavior: smooth;
}

/* Content Images */
.content-image {
    width: 100%;
    height: auto;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    margin: 1.5rem 0;
    transition: transform var(--transition-base);
}

.content-image:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}