/* CSS Variables */
:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary-color: #64748b;
    --accent-color: #f59e0b;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --border-radius: 8px;
}

/* Base Styles */
body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--bg-primary);
    margin: 0;
    padding: 0;
}

/* Japanese Font Override */
html[lang="ja"] body,
html[lang="ja"] h1, html[lang="ja"] h2, html[lang="ja"] h3, 
html[lang="ja"] h4, html[lang="ja"] h5, html[lang="ja"] h6, 
html[lang="ja"] p, html[lang="ja"] a, html[lang="ja"] ul, 
html[lang="ja"] li, html[lang="ja"] input, html[lang="ja"] button, 
html[lang="ja"] select, html[lang="ja"] textarea {
    font-family: 'Noto Sans JP', 'Yu Gothic', 'Meiryo', sans-serif;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 1rem;
}

.code-header {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

/* Header and Navigation */
.skip-link {
    position: absolute;
    top: -40px;
    left: 6px;
    background: var(--primary-color);
    color: white;
    padding: 8px;
    text-decoration: none;
    z-index: 100;
}

.skip-link:focus {
    top: 6px;
}

.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    height: 70px;
}

.navbar {
    height: 100%;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo h1 {
    margin: 0;
    font-size: 1.25rem;
    font-weight: 700;
}

.logo-link {
    text-decoration: none;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo-link:hover {
    color: var(--primary-color);
}

.nav-menu {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
    gap: 2rem;
}

.nav-menu a {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
    transition: var(--transition);
}

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

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: width 0.3s ease;
}

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

.nav-toggle {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    gap: 4px;
}

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

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

.lang-switch {
    display: flex;
    gap: 0.5rem;
}

.lang-btn {
    background: none;
    border: 1px solid var(--border-color);
    padding: 0.25rem 0.75rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.875rem;
    transition: var(--transition);
}

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

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

/* Hero Section */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.hero .hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.7) 0%, rgba(139, 92, 246, 0.5) 50%);
    z-index: 2;
}

/* Hero Video Background - Improved */
.hero-video-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    z-index: -2;
    background: linear-gradient(135deg, #2563eb 0%, #3b82f6 50%, #1d4ed8 100%);
}

.hero-video-bg video {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: opacity 0.3s ease;
}


/* Fallback when video fails */
.hero-video-bg.video-fallback {
    background: linear-gradient(135deg, #1e3a8a 0%, #3b82f6 25%, #2563eb 50%, #1d4ed8 75%, #1e40af 100%);
    background-size: 400% 400%;
    animation: gradientShift 8s ease-in-out infinite;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.8) 0%, rgba(139, 92, 246, 0.6) 100%);
    z-index: 2;
}

.hero-container {
    position: relative;
    z-index: 3;
    text-align: center;
    color: white;
    max-width: 1200px;
    padding: 0 2rem;
}

.hero-title {
    font-size: 4rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.hero-subtitle {
    font-size: 1.25rem;
    margin-bottom: 2.5rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
    opacity: 0.95;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

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

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 20px 25px -5px rgb(0 0 0 / 0.1);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.1);
    color: white;
    border: 2px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

.hero-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 2rem;
    max-width: 600px;
    margin: 0 auto;
}

.stat {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 1rem;
    opacity: 0.9;
}

/* Enhanced Overview Section */
.overview-intro {
    text-align: center;
    margin-bottom: 3rem;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.overview-intro p {
    font-size: 1.125rem;
    line-height: 1.7;
    color: var(--text-secondary);
}

.overview-features {
    margin-bottom: 3rem;
    padding: 2.5rem;
    background: white;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.overview-features h3 {
    text-align: center;
    margin-bottom: 2rem;
    font-size: 1.5rem;
    color: var(--text-primary);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.25rem;
}

.feature-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    padding: 1.25rem;
    background: var(--bg-secondary);
    border-radius: 8px;
    transition: var(--transition);
    border-left: 3px solid var(--primary-color);
}

.feature-item:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.feature-item i {
    color: var(--primary-color);
    font-size: 1.25rem;
    margin-top: 0.125rem;
    flex-shrink: 0;
}

.feature-item span {
    font-size: 0.95rem;
    line-height: 1.5;
    color: var(--text-secondary);
}

.feature-item strong {
    color: var(--text-primary);
}

.dataset-highlights {
    margin-top: 3rem;
    padding: 2.5rem;
    background: var(--bg-secondary);
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.dataset-highlights h3 {
    text-align: center;
    margin-bottom: 2rem;
    font-size: 1.5rem;
    color: var(--text-primary);
}

.highlights-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1rem;
}

.highlight-item {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
    padding: 1rem;
    background: white;
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
}

.highlight-item i {
    color: var(--primary-color);
    font-size: 1.125rem;
    margin-top: 0.125rem;
    flex-shrink: 0;
}

.highlight-item span {
    font-size: 0.95rem;
    line-height: 1.5;
    color: var(--text-secondary);
}

/* Overview Section */
.overview {
    padding: 5rem 0;
    background: var(--bg-secondary);
}

.overview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 3rem;
    margin-top: 3rem;
}

.overview-item {
    background: white;
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: var(--transition);
}

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

.overview-item .icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    color: white;
    font-size: 2rem;
}

.overview-item h3 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.overview-item p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Quick Links Section */
.quick-links {
    padding: 5rem 0;
    background: white;
}

.quick-links-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.quick-link-card {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
    display: block;
}

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

.quick-link-card .icon {
    width: 60px;
    height: 60px;
    background: var(--primary-color);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.quick-link-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.quick-link-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.5;
}

/* CTA Section */
.cta-section {
    padding: 5rem 0;
    background: var(--bg-secondary);
    text-align: center;
}

.cta-buttons {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    flex-wrap: wrap;
    margin-top: 2rem;
}

.btn-download {
    background: var(--primary-color);
    color: white;
    padding: 1rem 2.5rem;
    font-size: 1.1rem;
    font-weight: 600;
    box-shadow: var(--shadow-md);
    border: none;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.btn-csv-download {
    background: var(--primary-color);
    color: white;
    padding: 1rem 2.5rem;
    font-size: 1.1rem;
    font-weight: 100;
    box-shadow: var(--shadow-md);
    border: none;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

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

.btn-outline {
    background: white;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
    padding: 1rem 2.5rem;
    font-size: 1.1rem;
    font-weight: 600;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

.btn-outline:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    text-decoration: none;
}

/* Data Composition Section */
.data-composition {
    padding: 5rem 0;
    margin-top: -3rem;
    background: white;
}

.composition-content {
    max-width: 1000px;
    margin: 0 auto;
}

.composition-overview {
    text-align: center;
    margin-bottom: 3rem;
    font-size: 1.125rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.composition-table-container {
    overflow-x: auto;
    margin: 2rem 0 3rem 0;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
}

.composition-table {
    width: 100%;
    border-collapse: collapse;
    background: white;
    font-size: 0.95rem;
}

.composition-table th {
    background: var(--primary-color);
    color: white;
    padding: 1rem 0.75rem;
    text-align: left;
    font-weight: 600;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.composition-table td {
    padding: 0.875rem 0.75rem;
    border-bottom: 1px solid var(--border-color);
    vertical-align: middle;
}

.composition-table tbody tr:hover {
    background: var(--bg-secondary);
}

.composition-table tbody tr:nth-child(even) {
    background: rgba(248, 250, 252, 0.5);
}

.composition-table tbody tr:nth-child(even):hover {
    background: var(--bg-secondary);
}

.skill-badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    border-radius: 12px;
    font-size: 0.8rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.skill-badge.basic {
    background: #dcfce7;
    color: #166534;
}

.skill-badge.intermediate {
    background: #fef3c7;
    color: #92400e;
}

.skill-badge.advanced {
    background: #fecaca;
    color: #991b1b;
}

.total-row {
    background: var(--bg-secondary) !important;
    font-weight: 600;
    border-top: 2px solid var(--primary-color);
}

.total-row:hover {
    background: var(--bg-secondary) !important;
}

.composition-stats {
    margin-top: 3rem;
}

.stat-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.5rem;
}

.stat-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    padding: 1.5rem;
    background: var(--bg-secondary);
    border-radius: var(--border-radius);
    border-left: 4px solid var(--primary-color);
}

.stat-icon {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    background: var(--primary-color);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.25rem;
}

.stat-content h4 {
    margin: 0 0 0.5rem 0;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
}

.stat-content p {
    margin: 0;
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.4;
}

/* Page Header Styles */
.page-header {
    padding: 8rem 0 4rem 0;
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
    text-align: center;
}

/* Hero-style page header with video background */
.page-header.hero-style {
    position: relative;
    min-height: 20vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    overflow: hidden;
}

.page-header.hero-style .hero-video-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
}

.page-header.hero-style .hero-video-bg video {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.page-header.hero-style .hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.7) 0%, rgba(139, 92, 246, 0.5) 100%);
    z-index: 2;
}

.page-header.hero-style .container {
    position: relative;
    z-index: 3;
    color: white;
}

.page-header.hero-style h1 {
    color: white;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
    font-size: 3.5rem;
    font-weight: 800;
}

.page-header.hero-style p {
    color: rgba(255, 255, 255, 0.95);
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
    font-size: 1.3rem;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .page-header.hero-style {
        min-height: 25vh;
        padding: 3rem 0 2rem 0;
    }
    
    .page-header.hero-style h1 {
        font-size: 2.25rem;
    }
    
    .page-header.hero-style p {
        font-size: 1rem;
    }
}

@media (max-width: 480px) {
    .page-header.hero-style {
        min-height: 20vh;
    }
    
    .page-header.hero-style h1 {
        font-size: 1.875rem;
    }
}

/* Enhanced Dataset Statistics */
.dataset-stats {
    padding: 4rem 0;
    background: linear-gradient(135deg, #f8fafc, #e2e8f0);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.stat-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.07);
    display: flex;
    align-items: center;
    gap: 1.5rem;
    transition: all 0.3s ease;
    border: 1px solid rgba(99, 102, 241, 0.1);
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

.stat-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.5rem;
    flex-shrink: 0;
}


.stat-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.5rem;
    flex-shrink: 0;
}

.stat-content h3 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin: 0 0 0.25rem 0;
    line-height: 1;
}

.stat-content p {
    color: var(--text-light);
    font-weight: 500;
    margin: 0;
    font-size: 0.95rem;
}

/* Stats Breakdown */
.stats-breakdown {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.breakdown-section {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    border: 1px solid var(--border-color);
}

.breakdown-section h4 {
    margin: 0 0 1.5rem 0;
    color: var(--text-primary);
    font-weight: 600;
    font-size: 1.1rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--border-color);
}

.breakdown-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.breakdown-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem 1rem;
    background: #f8fafc;
    border-radius: 8px;
    transition: all 0.2s ease;
}

.breakdown-item:hover {
    background: #e2e8f0;
    transform: translateX(4px);
}

.breakdown-label {
    font-weight: 500;
    color: var(--text-primary);
    text-transform: capitalize;
}

.breakdown-value {
    font-weight: 600;
    color: var(--primary-color);
    font-size: 0.95rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .stats-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .stat-card {
        padding: 1.5rem;
        gap: 1rem;
    }
    
    .stat-icon {
        width: 50px;
        height: 50px;
        font-size: 1.25rem;
    }
    
    .stat-content h3 {
        font-size: 2rem;
    }
    
    .stats-breakdown {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .breakdown-section {
        padding: 1.5rem;
    }
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .composition-table {
        font-size: 0.85rem;
    }
    
    .composition-table th,
    .composition-table td {
        padding: 0.75rem 0.5rem;
    }
    
    .stat-item {
        padding: 1.25rem;
    }
    
    .stat-icon {
        width: 40px;
        height: 40px;
        font-size: 1.1rem;
    }
}

/* Responsive */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.125rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .page-header {
        padding: 6rem 0 3rem 0;
    }
    
    .page-header h1 {
        font-size: 2.25rem;
    }
    
    .page-stats {
        flex-direction: column;
        gap: 1.5rem;
    }
    
    .quick-start-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .header-links {
        flex-direction: column;
        align-items: center;
    }
}

/* Main content offset for fixed header */
main {
    margin-top: 70px;
}

.structure-item ul {
    margin-top: 0.5rem;
    padding-left: 1.5rem;
}

.structure-item li {
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.task-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
}

.task-item {
    background: white;
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    text-align: center;
    transition: var(--transition);
}

.task-item:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.task-item i {
    font-size: 1.5rem;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.task-item span {
    display: block;
    color: var(--text-primary);
    font-weight: 500;
}

/* Tools Section */
.tools {
    padding: 80px 0;
    background: var(--bg-primary);
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.tool-card {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.tool-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.tool-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: var(--border-radius);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
}

.tool-icon i {
    color: white;
    font-size: 1.5rem;
}

.tool-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.tool-card p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.tool-features {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.feature {
    background: var(--bg-accent);
    color: var(--primary-color);
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 500;
}

/* Download Section */
.download {
    padding: 80px 0;
    background: var(--bg-secondary);
}

.download-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: start;
}

.download-options {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.download-card {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.download-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.download-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.download-header i {
    font-size: 1.5rem;
    color: var(--primary-color);
}

.download-header h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
}

.download-info p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.download-stats {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.download-stats span {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-muted);
    font-size: 0.875rem;
}

.download-stats i {
    color: var(--primary-color);
}

.btn-download {
    background: #059669
    color: white;
    width: 100%;
    justify-content: center;
}

.btn-download:hover {
    background: #0dbe86;
    transform: translateY(-2px);
}

.download-instructions {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
}

.download-instructions h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
}

.code-block {
    background: var(--text-primary);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    overflow-x: auto;
}

.code-block pre {
    margin: 0;
}

.code-block code {
    color: #e2e8f0;
    font-family: 'Fira Code', monospace;
    font-size: 0.875rem;
    line-height: 1.6;
}

/* Documentation Section */
.documentation {
    padding: 80px 0;
    background: var(--bg-primary);
}

.docs-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.doc-card {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.doc-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.doc-icon {
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--accent-color), var(--primary-color));
    border-radius: var(--border-radius);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
}

.doc-icon i {
    color: white;
    font-size: 1.25rem;
}

.doc-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.doc-card p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.doc-link {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: var(--transition);
}

.doc-link:hover {
    color: var(--primary-dark);
}

/* Paper Section */
.paper {
    padding: 80px 0;
    background: var(--bg-secondary);
}

.paper-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
}

.paper-info h3,
.paper-abstract h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
}

.citation-block {
    background: var(--text-primary);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 2rem;
    overflow-x: auto;
}

.citation-block pre {
    margin: 0;
}

.citation-block code {
    color: #e2e8f0;
    font-family: 'Fira Code', monospace;
    font-size: 0.875rem;
    line-height: 1.6;
}

.paper-links {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.btn-paper {
    background: var(--primary-color);
    color: white;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

.paper-abstract p {
    color: var(--text-secondary);
    line-height: 1.8;
}

/* Footer */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 60px 0 20px;
}

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

.footer-section h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

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

.footer-section li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: #cbd5e1;
    text-decoration: none;
    transition: var(--transition);
}

.footer-section a:hover {
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid #374151;
    color: #9ca3af;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-title {
        font-size: 3rem;
    }
    
    .dataset-content,
    .download-content,
    .paper-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .hero {
        min-height: 80vh;
        padding: 100px 0 60px;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.125rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .hero-stats {
        justify-content: center;
    }
    
    .hero-overlay {
        background: rgba(0, 0, 0, 0.6);
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .overview-grid,
    .tools-grid,
    .docs-grid {
        grid-template-columns: 1fr;
    }
    
    .task-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .download-options {
        gap: 1rem;
    }
    
    .paper-links {
        flex-direction: column;
    }
    
    .hero,
    .overview,
    .dataset,
    .tools,
    .download,
    .documentation,
    .paper {
        padding: 60px 0;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: 1rem;
    }
    
    .task-grid {
        grid-template-columns: 1fr;
    }
    
    .download-stats {
        flex-direction: column;
        gap: 0.5rem;
    }
}

/* Smooth scrolling */
html {
    scroll-behavior: smooth;
}

/* Focus styles for accessibility */
button:focus,
a:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Animation for loading states */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in-up {
    animation: fadeInUp 0.6s ease-out;
}

/* Utility classes */
.text-center {
    text-align: center;
}

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

.text-right {
    text-align: right;
}

.mt-1 { margin-top: 0.25rem; }
.mt-2 { margin-top: 0.5rem; }
.mt-3 { margin-top: 0.75rem; }
.mt-4 { margin-top: 1rem; }
.mt-5 { margin-top: 1.25rem; }

.mb-1 { margin-bottom: 0.25rem; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-3 { margin-bottom: 0.75rem; }
.mb-4 { margin-bottom: 1rem; }
.mb-5 { margin-bottom: 1.25rem; }

.p-1 { padding: 0.25rem; }
.p-2 { padding: 0.5rem; }
.p-3 { padding: 0.75rem; }
.p-4 { padding: 1rem; }
.p-5 { padding: 1.25rem; }

/* Video Gallery Section */
.video-gallery {
    padding: 5rem 0;
    background: var(--bg-secondary);
}

.gallery-controls {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-bottom: 2rem;
    padding: 2rem;
    background: var(--bg-primary);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
}

.search-box {
    position: relative;
    max-width: 500px;
    width: 100%;
}

.search-box i {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
}

.search-box input {
    width: 100%;
    padding: 0.75rem 1rem 0.75rem 2.5rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
}

.search-box input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.filter-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    align-items: center;
}

.filter-controls select {
    padding: 0.5rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 0.9rem;
    cursor: pointer;
    transition: var(--transition);
}

.filter-controls select:focus {
    outline: none;
    border-color: var(--primary-color);
}

.btn-clear {
    padding: 0.5rem 1rem;
    background: var(--text-muted);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 0.9rem;
    transition: var(--transition);
}

.btn-clear:hover {
    background: var(--text-secondary);
}

.results-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    padding: 1rem 0;
}

.view-options {
    display: flex;
    gap: 0.5rem;
}

.view-btn {
    padding: 0.5rem;
    background: var(--bg-primary);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
}

.view-btn.active,
.view-btn:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

/* Video Grid */
.video-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.video-grid.list-view {
    grid-template-columns: 1fr;
}

.video-card {
    background: var(--bg-primary);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    cursor: pointer;
}

.video-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.video-card.list-view {
    display: flex;
    align-items: center;
}

.video-thumbnail {
    position: relative;
    width: 100%;
    aspect-ratio: 16/9;
    background: var(--bg-accent);
    overflow: hidden;
}

.video-card.list-view .video-thumbnail {
    width: 200px;
    flex-shrink: 0;
}

.video-thumbnail video {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.video-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.3);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: var(--transition);
}

.video-card:hover .video-overlay {
    opacity: 1;
}

.play-button {
    width: 60px;
    height: 60px;
    background: rgba(255, 255, 255, 0.9);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
    font-size: 1.5rem;
}

.video-info {
    padding: 1.5rem;
}

.video-card.list-view .video-info {
    flex: 1;
}

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

.video-description {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1rem;
    line-height: 1.5;
}

.video-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.meta-tag {
    padding: 0.25rem 0.75rem;
    background: var(--bg-accent);
    color: var(--text-secondary);
    border-radius: 1rem;
    font-size: 0.8rem;
    font-weight: 500;
}

.meta-tag.category {
    background: var(--primary-color);
    color: white;
}

.meta-tag.skill {
    background: var(--accent-color);
    color: white;
}

.video-stats {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1rem;
}

.pagination-btn {
    padding: 0.75rem 1.5rem;
    background: var(--bg-primary);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    font-size: 0.9rem;
}

.pagination-btn:hover:not(:disabled) {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.pagination-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.page-info {
    font-weight: 500;
    color: var(--text-secondary);
}

/* Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 1000;
    display: none;
    align-items: center;
    justify-content: center;
    padding: 1rem;
}

.modal.active {
    display: flex;
}

.modal-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(5px);
    z-index: 1001;
}

.modal-content {
    position: relative;
    background: var(--bg-primary);
    border-radius: var(--border-radius);
    max-width: 900px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: var(--shadow-xl);
    z-index: 1002;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

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

.modal-close:hover {
    color: var(--text-primary);
}

.modal-body {
    padding: 1.5rem;
}

.modal-video {
    margin-bottom: 2rem;
}

.modal-video video {
    width: 100%;
    border-radius: var(--border-radius);
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
}

.info-item {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.info-item label {
    font-weight: 600;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.info-item span {
    color: var(--text-primary);
    font-size: 1rem;
}

/* Loading states */
.loading-spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid var(--border-color);
    border-radius: 50%;
    border-top-color: var(--primary-color);
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.no-results {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-muted);
}

.no-results i {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--text-muted);
}

/* Data Chart Section */
.data-chart-section {
    margin-top: 4rem;
    padding: 2.5rem;
    background: white;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.data-chart-section h3 {
    text-align: center;
    margin-bottom: 2rem;
    font-size: 1.5rem;
    color: var(--text-primary);
}

.chart-container {
    max-width: 800px;
    margin: 0 auto;
}

.chart-tabs {
    display: flex;
    justify-content: center;
    margin-bottom: 2rem;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.chart-tab {
    padding: 0.75rem 1.5rem;
    border: 2px solid var(--border-color);
    background: white;
    color: var(--text-secondary);
    border-radius: 25px;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
    font-size: 0.9rem;
}

.chart-tab:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

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

.chart-wrapper {
    position: relative;
    height: 300px;
    width: 100%;
    background: var(--bg-secondary);
    border-radius: 8px;
    padding: 1rem;
}

.chart-wrapper canvas {
    border-radius: 8px;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .chart-tabs {
        flex-direction: column;
        align-items: center;
    }
    
    .chart-tab {
        width: 200px;
        text-align: center;
    }
    
    .chart-wrapper {
        height: 250px;
        padding: 0.5rem;
    }
}

/* Collapsible Summary Improvements */
.collapsible {
    margin: 2rem 0;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
    background: var(--card-bg);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.collapsible-summary {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 1.25rem 1.5rem;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    border: none;
    outline: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: relative;
    overflow: hidden;
}

.collapsible-summary:hover {
    background: linear-gradient(135deg, #1e40af, #059669);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.collapsible-summary:focus {
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.3);
}

.collapsible-summary::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(45deg, transparent 30%, rgba(255, 255, 255, 0.1) 50%, transparent 70%);
    transform: translateX(-100%);
    transition: transform 0.6s;
}

.collapsible-summary:hover::before {
    transform: translateX(100%);
}

.collapsible-summary::after {
    content: '\f107'; /* FontAwesome chevron-down */
    font-family: 'Font Awesome 6 Free';
    font-weight: 900;
    font-size: 1.2rem;
    transition: transform 0.3s ease;
    margin-left: auto;
    padding-left: 1rem;
}

.collapsible[open] .collapsible-summary::after {
    transform: rotate(180deg);
}

.collapsible-summary::-webkit-details-marker {
    display: none;
}

/* Slide animation container */
#composition-table-target {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.5s ease-in-out;
    background: var(--bg-primary);
}

.collapsible[open] #composition-table-target {
    max-height: 80vh; /* Limit height to 80% of viewport */
    overflow-y: auto;
}

/* Improve table container styling for scrollable view */
.composition-table-container {
    padding: 1.5rem;
    background: var(--bg-primary);
    max-height: 70vh;
    overflow-y: auto;
    overflow-x: auto;
}

.composition-table-container::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

.composition-table-container::-webkit-scrollbar-track {
    background: var(--bg-secondary);
    border-radius: 4px;
}

.composition-table-container::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

.composition-table-container::-webkit-scrollbar-thumb:hover {
    background: var(--text-secondary);
}

/* Table improvements for better mobile experience */
@media (max-width: 768px) {
    .composition-table-container {
        max-height: 60vh;
        padding: 1rem;
    }
    
    .collapsible[open] #composition-table-target {
        max-height: 70vh;
    }
}

/* CSS Variables */
:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary-color: #64748b;
    --accent-color: #f59e0b;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --border-radius: 8px;
}

/* Base Styles */
body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--bg-primary);
    margin: 0;
    padding: 0;
}

/* Japanese Font Override */
html[lang="ja"] body,
html[lang="ja"] h1, html[lang="ja"] h2, html[lang="ja"] h3, 
html[lang="ja"] h4, html[lang="ja"] h5, html[lang="ja"] h6, 
html[lang="ja"] p, html[lang="ja"] a, html[lang="ja"] ul, 
html[lang="ja"] li, html[lang="ja"] input, html[lang="ja"] button, 
html[lang="ja"] select, html[lang="ja"] textarea {
    font-family: 'Noto Sans JP', 'Yu Gothic', 'Meiryo', sans-serif;
}

.skip-link:focus {
    top: 6px;
}

.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    height: 70px;
}

.navbar {
    height: 100%;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo h1 {
    margin: 0;
    font-size: 1.25rem;
    font-weight: 700;
}

.logo-link {
    text-decoration: none;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo-link:hover {
    color: var(--primary-color);
}

.nav-menu {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
    gap: 2rem;
}

.nav-menu a {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
    transition: var(--transition);
}

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

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: width 0.3s ease;
}

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

.nav-toggle {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    gap: 4px;
}

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

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

.lang-switch {
    display: flex;
    gap: 0.5rem;
}

.lang-btn {
    background: none;
    border: 1px solid var(--border-color);
    padding: 0.25rem 0.75rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.875rem;
    transition: var(--transition);
}

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

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

/* Hero Section */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.hero-video-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
}

.hero-video-bg video {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.8) 0%, rgba(139, 92, 246, 0.6) 100%);
    z-index: 2;
}

.hero-container {
    position: relative;
    z-index: 3;
    text-align: center;
    color: white;
    max-width: 1200px;
    padding: 0 2rem;
}

.hero-title {
    font-size: 4rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.hero-subtitle {
    font-size: 1.25rem;
    margin-bottom: 2.5rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
    opacity: 0.95;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

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

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 20px 25px -5px rgb(0 0 0 / 0.1);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.1);
    color: white;
    border: 2px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

.hero-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 2rem;
    max-width: 600px;
    margin: 0 auto;
}

.stat {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 1rem;
    opacity: 0.9;
}

/* Enhanced Overview Section */
.overview-intro {
    text-align: center;
    margin-bottom: 3rem;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.overview-intro p {
    font-size: 1.125rem;
    line-height: 1.7;
    color: var(--text-secondary);
}

.overview-features {
    margin-bottom: 3rem;
    padding: 2.5rem;
    background: white;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.overview-features h3 {
    text-align: center;
    margin-bottom: 2rem;
    font-size: 1.5rem;
    color: var(--text-primary);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.25rem;
}

.feature-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    padding: 1.25rem;
    background: var(--bg-secondary);
    border-radius: 8px;
    transition: var(--transition);
    border-left: 3px solid var(--primary-color);
}

.feature-item:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.feature-item i {
    color: var(--primary-color);
    font-size: 1.25rem;
    margin-top: 0.125rem;
    flex-shrink: 0;
}

.feature-item span {
    font-size: 0.95rem;
    line-height: 1.5;
    color: var(--text-secondary);
}

.feature-item strong {
    color: var(--text-primary);
}

.dataset-highlights {
    margin-top: 3rem;
    padding: 2.5rem;
    background: var(--bg-secondary);
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.dataset-highlights h3 {
    text-align: center;
    margin-bottom: 2rem;
    font-size: 1.5rem;
    color: var(--text-primary);
}

.highlights-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1rem;
}

.highlight-item {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
    padding: 1rem;
    background: white;
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
}

.highlight-item i {
    color: var(--primary-color);
    font-size: 1.125rem;
    margin-top: 0.125rem;
    flex-shrink: 0;
}

.highlight-item span {
    font-size: 0.95rem;
    line-height: 1.5;
    color: var(--text-secondary);
}

/* Overview Section */
.overview {
    padding: 5rem 0;
    background: var(--bg-secondary);
}

.overview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 3rem;
    margin-top: 3rem;
}

.overview-item {
    background: white;
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: var(--transition);
}

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

.overview-item .icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    color: white;
    font-size: 2rem;
}

.overview-item h3 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.overview-item p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Quick Links Section */
.quick-links {
    padding: 5rem 0;
    background: white;
}

.quick-links-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.quick-link-card {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
    display: block;
}

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

.quick-link-card .icon {
    width: 60px;
    height: 60px;
    background: var(--primary-color);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.quick-link-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.quick-link-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.5;
}

/* CTA Section */
.cta-section {
    padding: 5rem 0;
    background: var(--bg-secondary);
    text-align: center;
}

.cta-buttons {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    flex-wrap: wrap;
    margin-top: 2rem;
}

.btn-download {
    background: var(--primary-color);
    color: white;
    padding: 1rem 2.5rem;
    font-size: 1.1rem;
    font-weight: 600;
    box-shadow: var(--shadow-md);
    border: none;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

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

.btn-outline {
    background: white;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
    padding: 1rem 2.5rem;
    font-size: 1.1rem;
    font-weight: 600;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

.btn-outline:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    text-decoration: none;
}

/* Data Composition Section */
.data-composition {
    padding: 5rem 0;
    background: white;
}

.composition-content {
    max-width: 1000px;
    margin: 0 auto;
}

.composition-overview {
    text-align: center;
    margin-bottom: 3rem;
    font-size: 1.125rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.composition-table-container {
    overflow-x: auto;
    margin: 2rem 0 3rem 0;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
}

.composition-table {
    width: 100%;
    border-collapse: collapse;
    background: white;
    font-size: 0.95rem;
}

.composition-table th {
    background: var(--primary-color);
    color: white;
    padding: 1rem 0.75rem;
    text-align: left;
    font-weight: 600;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.composition-table td {
    padding: 0.875rem 0.75rem;
    border-bottom: 1px solid var(--border-color);
    vertical-align: middle;
}

.composition-table tbody tr:hover {
    background: var(--bg-secondary);
}

.composition-table tbody tr:nth-child(even) {
    background: rgba(248, 250, 252, 0.5);
}

.composition-table tbody tr:nth-child(even):hover {
    background: var(--bg-secondary);
}

.skill-badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    border-radius: 12px;
    font-size: 0.8rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.skill-badge.basic {
    background: #dcfce7;
    color: #166534;
}

.skill-badge.intermediate {
    background: #fef3c7;
    color: #92400e;
}

.skill-badge.advanced {
    background: #fecaca;
    color: #991b1b;
}

.total-row {
    background: var(--bg-secondary) !important;
    font-weight: 600;
    border-top: 2px solid var(--primary-color);
}

.total-row:hover {
    background: var(--bg-secondary) !important;
}

.composition-stats {
    margin-top: 3rem;
}

.stat-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.5rem;
}

.stat-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    padding: 1.5rem;
    background: var(--bg-secondary);
    border-radius: var(--border-radius);
    border-left: 4px solid var(--primary-color);
}

.stat-icon {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    background: var(--primary-color);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.25rem;
}

.stat-content h4 {
    margin: 0 0 0.5rem 0;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
}

.stat-content p {
    margin: 0;
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.4;
}

/* Page Header Styles */
.page-header {
    padding: 8rem 0 4rem 0;
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
    text-align: center;
}

/* Hero-style page header with video background */
.page-header.hero-style {
    position: relative;
    min-height: 20vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    overflow: hidden;
}

.page-header.hero-style .hero-video-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
}

.page-header.hero-style .hero-video-bg video {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.page-header.hero-style .hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.7) 0%, rgba(139, 92, 246, 0.5) 50%);
    z-index: 2;
}

.page-header.hero-style .container {
    position: relative;
    z-index: 3;
    color: white;
}

.page-header.hero-style h1 {
    color: white;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
    font-size: 3.5rem;
    font-weight: 800;
}

.page-header.hero-style p {
    color: rgba(255, 255, 255, 0.95);
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
    font-size: 1.3rem;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .page-header.hero-style {
        min-height: 25vh;
        padding: 3rem 0 2rem 0;
    }
    
    .page-header.hero-style h1 {
        font-size: 2.25rem;
    }
    
    .page-header.hero-style p {
        font-size: 1rem;
    }
}

@media (max-width: 480px) {
    .page-header.hero-style {
        min-height: 20vh;
    }
    
    .page-header.hero-style h1 {
        font-size: 1.875rem;
    }
}

/* Enhanced Dataset Statistics */
.dataset-stats {
    padding: 4rem 0;
    background: linear-gradient(135deg, #f8fafc, #e2e8f0);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}


.stat-content h3 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin: 0 0 0.25rem 0;
    line-height: 1;
}

.stat-content p {
    color: var(--text-light);
    font-weight: 500;
    margin: 0;
    font-size: 0.95rem;
}

/* Stats Breakdown */
.stats-breakdown {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.breakdown-section {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    border: 1px solid var(--border-color);
}

.breakdown-section h4 {
    margin: 0 0 1.5rem 0;
    color: var(--text-primary);
    font-weight: 600;
    font-size: 1.1rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--border-color);
}

.breakdown-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.breakdown-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem 1rem;
    background: #f8fafc;
    border-radius: 8px;
    transition: all 0.2s ease;
}

.breakdown-item:hover {
    background: #e2e8f0;
    transform: translateX(4px);
}

.breakdown-label {
    font-weight: 500;
    color: var(--text-primary);
    text-transform: capitalize;
}

.breakdown-value {
    font-weight: 600;
    color: var(--primary-color);
    font-size: 0.95rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .stats-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .stat-card {
        padding: 1.5rem;
        gap: 1rem;
    }
    
    .stat-icon {
        width: 50px;
        height: 50px;
        font-size: 1.25rem;
    }
    
    .stat-content h3 {
        font-size: 2rem;
    }
    
    .stats-breakdown {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .breakdown-section {
        padding: 1.5rem;
    }
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .composition-table {
        font-size: 0.85rem;
    }
    
    .composition-table th,
    .composition-table td {
        padding: 0.75rem 0.5rem;
    }
    
    .stat-item {
        padding: 1.25rem;
    }
    
    .stat-icon {
        width: 40px;
        height: 40px;
        font-size: 1.1rem;
    }
}

/* Responsive */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.125rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .page-header {
        padding: 6rem 0 3rem 0;
    }
    
    .page-header h1 {
        font-size: 2.25rem;
    }
    
    .page-stats {
        flex-direction: column;
        gap: 1.5rem;
    }
    
    .quick-start-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .header-links {
        flex-direction: column;
        align-items: center;
    }
}

/* Main content offset for fixed header */
main {
    margin-top: 70px;
}

.structure-item ul {
    margin-top: 0.5rem;
    padding-left: 1.5rem;
}

.structure-item li {
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.task-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
}

.task-item {
    background: white;
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    text-align: center;
    transition: var(--transition);
}

.task-item:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.task-item i {
    font-size: 1.5rem;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.task-item span {
    display: block;
    color: var(--text-primary);
    font-weight: 500;
}

/* Tools Section */
.tools {
    padding: 80px 0;
    background: var(--bg-primary);
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.tool-card {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.tool-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.tool-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: var(--border-radius);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
}

.tool-icon i {
    color: white;
    font-size: 1.5rem;
}

.tool-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.tool-card p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.tool-features {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.feature {
    background: var(--bg-accent);
    color: var(--primary-color);
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 500;
}

/* Download Section */
.download {
    padding: 80px 0;
    background: var(--bg-secondary);
}

.download-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: start;
}

.download-options {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.download-card {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.download-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.download-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.download-header i {
    font-size: 1.5rem;
    color: var(--primary-color);
}

.download-header h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
}

.download-info p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.download-stats {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.download-stats span {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-muted);
    font-size: 0.875rem;
}

.download-stats i {
    color: var(--primary-color);
}

.btn-download {
    background: #059669
    color: white;
    width: 100%;
    justify-content: center;
}

.btn-download:hover {
    background: #0dbe86;
    transform: translateY(-2px);
}

.download-instructions {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
}

.download-instructions h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
}

.code-block {
    background: var(--text-primary);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    overflow-x: auto;
}

.code-block pre {
    margin: 0;
}

.code-block code {
    color: #e2e8f0;
    font-family: 'Fira Code', monospace;
    font-size: 0.875rem;
    line-height: 1.6;
}

/* Documentation Section */
.documentation {
    padding: 80px 0;
    background: var(--bg-primary);
}

.docs-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.doc-card {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.doc-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.doc-icon {
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--accent-color), var(--primary-color));
    border-radius: var(--border-radius);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
}

.doc-icon i {
    color: white;
    font-size: 1.25rem;
}

.doc-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.doc-card p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.doc-link {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: var(--transition);
}

.doc-link:hover {
    color: var(--primary-dark);
}

/* Paper Section */
.paper {
    padding: 80px 0;
    background: var(--bg-secondary);
}

.paper-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
}

.paper-info h3,
.paper-abstract h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
}

.citation-block {
    background: var(--text-primary);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 2rem;
    overflow-x: auto;
}

.citation-block pre {
    margin: 0;
}

.citation-block code {
    color: #e2e8f0;
    font-family: 'Fira Code', monospace;
    font-size: 0.875rem;
    line-height: 1.6;
}

.paper-links {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.btn-paper {
    background: var(--primary-color);
    color: white;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

.paper-abstract p {
    color: var(--text-secondary);
    line-height: 1.8;
}

/* Footer */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 60px 0 20px;
}

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

.footer-section h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

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

.footer-section li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: #cbd5e1;
    text-decoration: none;
    transition: var(--transition);
}

.footer-section a:hover {
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid #374151;
    color: #9ca3af;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-title {
        font-size: 3rem;
    }
    
    .dataset-content,
    .download-content,
    .paper-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .hero {
        min-height: 80vh;
        padding: 100px 0 60px;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.125rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .hero-stats {
        justify-content: center;
    }
    
    .hero-overlay {
        background: rgba(0, 0, 0, 0.6);
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .overview-grid,
    .tools-grid,
    .docs-grid {
        grid-template-columns: 1fr;
    }
    
    .task-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .download-options {
        gap: 1rem;
    }
    
    .paper-links {
        flex-direction: column;
    }
    
    .hero,
    .overview,
    .dataset,
    .tools,
    .download,
    .documentation,
    .paper {
        padding: 60px 0;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: 1rem;
    }
    
    .task-grid {
        grid-template-columns: 1fr;
    }
    
    .download-stats {
        flex-direction: column;
        gap: 0.5rem;
    }
}

/* Smooth scrolling */
html {
    scroll-behavior: smooth;
}

/* Focus styles for accessibility */
button:focus,
a:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Animation for loading states */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in-up {
    animation: fadeInUp 0.6s ease-out;
}

/* Utility classes */
.text-center {
    text-align: center;
}

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

.text-right {
    text-align: right;
}

.mt-1 { margin-top: 0.25rem; }
.mt-2 { margin-top: 0.5rem; }
.mt-3 { margin-top: 0.75rem; }
.mt-4 { margin-top: 1rem; }
.mt-5 { margin-top: 1.25rem; }

.mb-1 { margin-bottom: 0.25rem; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-3 { margin-bottom: 0.75rem; }
.mb-4 { margin-bottom: 1rem; }
.mb-5 { margin-bottom: 1.25rem; }

.p-1 { padding: 0.25rem; }
.p-2 { padding: 0.5rem; }
.p-3 { padding: 0.75rem; }
.p-4 { padding: 1rem; }
.p-5 { padding: 1.25rem; }

/* Video Gallery Section */
.video-gallery {
    padding: 5rem 0;
    background: var(--bg-secondary);
}

.gallery-controls {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-bottom: 2rem;
    padding: 2rem;
    background: var(--bg-primary);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
}

.search-box {
    position: relative;
    max-width: 500px;
    width: 100%;
}

.search-box i {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
}

.search-box input {
    width: 100%;
    padding: 0.75rem 1rem 0.75rem 2.5rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
}

.search-box input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.filter-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    align-items: center;
}

.filter-controls select {
    padding: 0.5rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 0.9rem;
    cursor: pointer;
    transition: var(--transition);
}

.filter-controls select:focus {
    outline: none;
    border-color: var(--primary-color);
}

.btn-clear {
    padding: 0.5rem 1rem;
    background: var(--text-muted);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 0.9rem;
    transition: var(--transition);
}

.btn-clear:hover {
    background: var(--text-secondary);
}

.results-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    padding: 1rem 0;
}

.view-options {
    display: flex;
    gap: 0.5rem;
}

.view-btn {
    padding: 0.5rem;
    background: var(--bg-primary);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
}

.view-btn.active,
.view-btn:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

/* Video Grid */
.video-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.video-grid.list-view {
    grid-template-columns: 1fr;
}

.video-card {
    background: var(--bg-primary);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    cursor: pointer;
}

.video-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.video-card.list-view {
    display: flex;
    align-items: center;
}

.video-thumbnail {
    position: relative;
    width: 100%;
    aspect-ratio: 16/9;
    background: var(--bg-accent);
    overflow: hidden;
}

.video-card.list-view .video-thumbnail {
    width: 200px;
    flex-shrink: 0;
}

.video-thumbnail video {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.video-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.3);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: var(--transition);
}

.video-card:hover .video-overlay {
    opacity: 1;
}

.play-button {
    width: 60px;
    height: 60px;
    background: rgba(255, 255, 255, 0.9);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
    font-size: 1.5rem;
}

.video-info {
    padding: 1.5rem;
}

.video-card.list-view .video-info {
    flex: 1;
}

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

.video-description {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1rem;
    line-height: 1.5;
}

.video-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.meta-tag {
    padding: 0.25rem 0.75rem;
    background: var(--bg-accent);
    color: var(--text-secondary);
    border-radius: 1rem;
    font-size: 0.8rem;
    font-weight: 500;
}

.meta-tag.category {
    background: var(--primary-color);
    color: white;
}

.meta-tag.skill {
    background: var(--accent-color);
    color: white;
}

.video-stats {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1rem;
}

.pagination-btn {
    padding: 0.75rem 1.5rem;
    background: var(--bg-primary);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    font-size: 0.9rem;
}

.pagination-btn:hover:not(:disabled) {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.pagination-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.page-info {
    font-weight: 500;
    color: var(--text-secondary);
}

/* Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 1000;
    display: none;
    align-items: center;
    justify-content: center;
    padding: 1rem;
}

.modal.active {
    display: flex;
}

.modal-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(5px);
    z-index: 1001;
}

.modal-content {
    position: relative;
    background: var(--bg-primary);
    border-radius: var(--border-radius);
    max-width: 900px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: var(--shadow-xl);
    z-index: 1002;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

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

.modal-close:hover {
    color: var(--text-primary);
}

.modal-body {
    padding: 1.5rem;
}

.modal-video {
    margin-bottom: 2rem;
}

.modal-video video {
    width: 100%;
    border-radius: var(--border-radius);
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
}

.info-item {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.info-item label {
    font-weight: 600;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.info-item span {
    color: var(--text-primary);
    font-size: 1rem;
}

/* Loading states */
.loading-spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid var(--border-color);
    border-radius: 50%;
    border-top-color: var(--primary-color);
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.no-results {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-muted);
}

.no-results i {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--text-muted);
}

/* Data Chart Section */
.data-chart-section {
    margin-top: 4rem;
    padding: 2.5rem;
    background: white;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.data-chart-section h3 {
    text-align: center;
    margin-bottom: 2rem;
    font-size: 1.5rem;
    color: var(--text-primary);
}

.chart-container {
    max-width: 800px;
    margin: 0 auto;
}

.chart-tabs {
    display: flex;
    justify-content: center;
    margin-bottom: 2rem;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.chart-tab {
    padding: 0.75rem 1.5rem;
    border: 2px solid var(--border-color);
    background: white;
    color: var(--text-secondary);
    border-radius: 25px;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
    font-size: 0.9rem;
}

.chart-tab:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

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

.chart-wrapper {
    position: relative;
    height: 300px;
    width: 100%;
    background: var(--bg-secondary);
    border-radius: 8px;
    padding: 1rem;
}

.chart-wrapper canvas {
    border-radius: 8px;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .chart-tabs {
        flex-direction: column;
        align-items: center;
    }
    
    .chart-tab {
        width: 200px;
        text-align: center;
    }
    
    .chart-wrapper {
        height: 250px;
        padding: 0.5rem;
    }
}

/* Collapsible Summary Improvements */
.collapsible {
    margin: 2rem 0;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
    background: var(--card-bg);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.collapsible-summary {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 1.25rem 1.5rem;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    border: none;
    outline: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: relative;
    overflow: hidden;
}

.collapsible-summary:hover {
    background: linear-gradient(135deg, #1e40af, #059669);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.collapsible-summary:focus {
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.3);
}

.collapsible-summary::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(45deg, transparent 30%, rgba(255, 255, 255, 0.1) 50%, transparent 70%);
    transform: translateX(-100%);
    transition: transform 0.6s;
}

.collapsible-summary:hover::before {
    transform: translateX(100%);
}

.collapsible-summary::after {
    content: '\f107'; /* FontAwesome chevron-down */
    font-family: 'Font Awesome 6 Free';
    font-weight: 900;
    font-size: 1.2rem;
    transition: transform 0.3s ease;
    margin-left: auto;
    padding-left: 1rem;
}

.collapsible[open] .collapsible-summary::after {
    transform: rotate(180deg);
}

.collapsible-summary::-webkit-details-marker {
    display: none;
}

/* Slide animation container */
#composition-table-target {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.5s ease-in-out;
    background: var(--bg-primary);
}

.collapsible[open] #composition-table-target {
    max-height: 80vh; /* Limit height to 80% of viewport */
    overflow-y: auto;
}

/* Improve table container styling for scrollable view */
.composition-table-container {
    padding: 1.5rem;
    background: var(--bg-primary);
    max-height: 70vh;
    overflow-y: auto;
    overflow-x: auto;
}

.composition-table-container::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

.composition-table-container::-webkit-scrollbar-track {
    background: var(--bg-secondary);
    border-radius: 4px;
}

.composition-table-container::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

.composition-table-container::-webkit-scrollbar-thumb:hover {
    background: var(--text-secondary);
}

/* Table improvements for better mobile experience */
@media (max-width: 768px) {
    .composition-table-container {
        max-height: 60vh;
        padding: 1rem;
    }
    
    .collapsible[open] #composition-table-target {
        max-height: 70vh;
    }
}

/* CSS Variables */
:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary-color: #64748b;
    --accent-color: #f59e0b;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --border-radius: 8px;
}

/* Base Styles */
body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--bg-primary);
    margin: 0;
    padding: 0;
}

/* Japanese Font Override */
html[lang="ja"] body,
html[lang="ja"] h1, html[lang="ja"] h2, html[lang="ja"] h3, 
html[lang="ja"] h4, html[lang="ja"] h5, html[lang="ja"] h6, 
html[lang="ja"] p, html[lang="ja"] a, html[lang="ja"] ul, 
html[lang="ja"] li, html[lang="ja"] input, html[lang="ja"] button, 
html[lang="ja"] select, html[lang="ja"] textarea {
    font-family: 'Noto Sans JP', 'Yu Gothic', 'Meiryo', sans-serif;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

/* Header and Navigation */
.skip-link {
    position: absolute;
    top: -40px;
    left: 6px;
    background: var(--primary-color);
    color: white;
    padding: 8px;
    text-decoration: none;
    z-index: 100;
}

.skip-link:focus {
    top: 6px;
}

.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    height: 70px;
}

.navbar {
    height: 100%;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo h1 {
    margin: 0;
    font-size: 1.25rem;
    font-weight: 700;
}

.logo-link {
    text-decoration: none;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo-link:hover {
    color: var(--primary-color);
}

.nav-menu {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
    gap: 2rem;
}

.nav-menu a {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
    transition: var(--transition);
}

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

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: width 0.3s ease;
}

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

.nav-toggle {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    gap: 4px;
}

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

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

.lang-switch {
    display: flex;
    gap: 0.5rem;
}

.lang-btn {
    background: none;
    border: 1px solid var(--border-color);
    padding: 0.25rem 0.75rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.875rem;
    transition: var(--transition);
}

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

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

/* Hero Section */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

/* Hero Video Background - Improved */
.hero-video-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    z-index: -2;
    background: linear-gradient(135deg, #2563eb 0%, #3b82f6 50%, #1d4ed8 100%);
}

.hero-video-bg video {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: opacity 0.3s ease;
}

/* Fallback when video fails */
.hero-video-bg.video-fallback {
    background: linear-gradient(135deg, #1e3a8a 0%, #3b82f6 25%, #2563eb 50%, #1d4ed8 75%, #1e40af 100%);
    background-size: 400% 400%;
    animation: gradientShift 8s ease-in-out infinite;
}

@keyframes gradientShift {
    0%, 100% {
        background-position: 0% 50%;
    }
    50% {
        background-position: 100% 50%;
    }
}

.hero-video-bg.video-fallback video {
    display: none;
}

/* Hero overlay */
.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.8) 0%, rgba(139, 92, 246, 0.6) 100%);
    z-index: -1;
}

/* Page header fallback */
.page-header.hero-style .hero-video-bg.video-fallback {
    background: linear-gradient(135deg, #4f46e5 0%, #7c3aed 50%, #6366f1 100%);
    background-size: 400% 400%;
    animation: gradientShift 8s ease-in-out infinite;
}

.hero-container {
    position: relative;
    z-index: 3;
    text-align: center;
    color: white;
    max-width: 1400px;
    padding: 0 2rem;
}

.hero-title {
    font-size: 4rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.hero-subtitle {
    font-size: 1.25rem;
    margin-bottom: 2.5rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
    opacity: 0.95;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

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

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 20px 25px -5px rgb(0 0 0 / 0.1);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.1);
    color: white;
    border: 2px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

.hero-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 2rem;
    max-width: 600px;
    margin: 0 auto;
}

.stat {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 1rem;
    opacity: 0.9;
}

/* Enhanced Overview Section */
.overview-intro {
    text-align: center;
    margin-bottom: 3rem;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.overview-intro p {
    font-size: 1.125rem;
    line-height: 1.7;
    color: var(--text-secondary);
}

.overview-features {
    margin-bottom: 3rem;
    padding: 2.5rem;
    background: white;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.overview-features h3 {
    text-align: center;
    margin-bottom: 2rem;
    font-size: 1.5rem;
    color: var(--text-primary);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.25rem;
}

.feature-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    padding: 1.25rem;
    background: var(--bg-secondary);
    border-radius: 8px;
    transition: var(--transition);
    border-left: 3px solid var(--primary-color);
}

.feature-item:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.feature-item i {
    color: var(--primary-color);
    font-size: 1.25rem;
    margin-top: 0.125rem;
    flex-shrink: 0;
}

.feature-item span {
    font-size: 0.95rem;
    line-height: 1.5;
    color: var(--text-secondary);
}

.feature-item strong {
    color: var(--text-primary);
}

.dataset-highlights {
    margin-top: 3rem;
    padding: 2.5rem;
    background: var(--bg-secondary);
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.dataset-highlights h3 {
    text-align: center;
    margin-bottom: 2rem;
    font-size: 1.5rem;
    color: var(--text-primary);
}

.highlights-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1rem;
}

.highlight-item {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
    padding: 1rem;
    background: white;
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
}

.highlight-item i {
    color: var(--primary-color);
    font-size: 1.125rem;
    margin-top: 0.125rem;
    flex-shrink: 0;
}

.highlight-item span {
    font-size: 0.95rem;
    line-height: 1.5;
    color: var(--text-secondary);
}

/* Overview Section */
.overview {
    padding: 3rem 0;
    background: var(--bg-secondary);
}

.overview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 3rem;
    margin-top: 3rem;
}

.overview-item {
    background: white;
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: var(--transition);
}

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

.overview-item .icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    color: white;
    font-size: 2rem;
}

.overview-item h3 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.overview-item p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Quick Links Section */
.quick-links {
    padding: 3rem 0;
    background: white;
}

.quick-links-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.quick-link-card {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
    display: block;
}

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

.quick-link-card .icon {
    width: 60px;
    height: 60px;
    background: var(--primary-color);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.quick-link-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.quick-link-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.5;
}

/* CTA Section */
.cta-section {
    padding: 3rem 0;
    background: var(--bg-secondary);
    text-align: center;
}

.cta-buttons {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    flex-wrap: wrap;
    margin-top: 2rem;
}

.btn-download {
    background: var(--primary-color);
    color: white;
    padding: 1rem 2.5rem;
    font-size: 1.1rem;
    font-weight: 600;
    box-shadow: var(--shadow-md);
    border: none;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

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

.btn-outline {
    background: white;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
    padding: 1rem 2.5rem;
    font-size: 1.1rem;
    font-weight: 600;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

.btn-outline:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    text-decoration: none;
}

/* Data Composition Section */
.data-composition {
    padding: 3rem 0;
    background: white;
}

.composition-content {
    max-width: 1300px;
    margin: 0 auto;
}

.composition-overview {
    text-align: center;
    margin-bottom: 3rem;
    font-size: 1.125rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* Data Composition Table Styles - Full Width Responsive Design */
.composition-table-container {
    width: 100%;
    overflow: visible;
    margin: 2rem 0;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    background: white;
}

.composition-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.85rem;
    line-height: 1.4;
    table-layout: auto;
}

.composition-table caption {
    padding: 1rem;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--primary-color);
    text-align: left;
    background: #f8fafc;
    border-bottom: 2px solid #e2e8f0;
}

.composition-table th,
.composition-table td {
    padding: 0.75rem 0.5rem;
    text-align: left;
    border-bottom: 1px solid #e2e8f0;
    vertical-align: top;
    word-wrap: break-word;
    overflow-wrap: break-word;
}

.composition-table th {
    background: #f1f5f9;
    font-weight: 600;
    color: var(--text-dark);
    position: sticky;
    top: 0;
    z-index: 10;
}

.composition-table tbody tr:hover {
    background-color: #f8fafc;
}

.composition-table img {
    max-width: 80px;
    height: auto;
    border-radius: 4px;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
}

.composition-table .total-row {
    background-color: #e2e8f0 !important;
    font-weight: 600;
}

/* Data Composition Section Styles */
#composition-table-target {
    width: 100%;
    margin: 2rem 0;
    min-height: 200px;
}

/* Load More Section Styles - Enhanced for Better Visibility */
.load-more-section {
    text-align: center;
    padding: 2rem 1rem;
    border-top: 2px solid #e2e8f0;
    margin-top: 1.5rem;
    background: linear-gradient(to bottom, #f8fafc, #f1f5f9);
    border-radius: 0 0 8px 8px;
    clear: both;
    width: 100%;
    display: block;
}

.load-more-btn {
    padding: 1rem 2.5rem;
    font-size: 1rem;
    font-weight: 600;
    border: 2px solid var(--primary-color) !important;
    background: white !important;
    color: var(--primary-color) !important;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex !important;
    align-items: center;
    gap: 0.75rem;
    text-decoration: none;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    min-width: 250px;
    justify-content: center;
    position: relative;
    z-index: 100;
}

.load-more-btn:hover {
    background: var(--primary-color) !important;
    color: white !important;
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(37, 99, 235, 0.4);
}

.load-more-btn:active {
    transform: translateY(0);
}

.load-more-btn i {
    transition: transform 0.3s ease;
    font-size: 1.1rem;
}

.load-more-btn:hover i {
    transform: translateY(3px);
}

/* Ensure visibility and proper layout */
#composition-table-target {
    width: 100%;
    margin: 2rem 0;
    min-height: 300px;
    position: relative;
}

#composition-table-target .load-more-section {
    display: block !important;
    visibility: visible !important;
    opacity: 1 !important;
}

/* Composition Table Container */
.composition-table-container {
    width: 100%;
    overflow: visible;
    margin: 1rem 0;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    background: white;
    border: 1px solid #e2e8f0;
    position: relative;
}

/* Loading and error states */
#composition-table-target .fas.fa-spinner {
    font-size: 1.5rem;
    color: var(--primary-color);
}

/* Responsive design */
@media (max-width: 768px) {
    .composition-table {
        font-size: 0.75rem;
    }
    
    .composition-table th,
    .composition-table td {
        padding: 0.5rem 0.3rem;
    }
    
    .composition-table img {
        max-width: 60px;
    }
    
    .load-more-btn {
        padding: 0.6rem 1.5rem;
        font-size: 0.9rem;
    }
}


/* Mobile Navigation Styles */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: white;
        box-shadow: var(--shadow-lg);
        flex-direction: column;
        padding: 1rem 0;
        z-index: 1000;
        border-top: 1px solid var(--border-color);
    }
    
    .nav-menu.open {
        display: flex;
    }
    
    .nav-menu li {
        margin: 0;
        text-align: center;
    }
    
    .nav-menu a {
        display: block;
        padding: 1rem;
        border-bottom: 1px solid var(--border-color);
    }
    
    .nav-toggle {
        display: flex !important;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.125rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .composition-table {
        font-size: 0.75rem;
    }
    
    .composition-table th,
    .composition-table td {
        padding: 0.5rem 0.3rem;
    }
    
    .composition-table img {
        max-width: 60px;
    }
}