:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary-color: #64748b;
    --accent-color: #f59e0b;
    --bg-color: #ffffff;
    --bg-secondary: #f8fafc;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --radius: 8px;
    --max-width: 1200px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-color);
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1rem;
}

/* Header */
.header {
    background: var(--bg-color);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem;
    max-width: var(--max-width);
    margin: 0 auto;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 600;
    font-size: 1.25rem;
}

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

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    transition: color 0.2s;
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-color);
}

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

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    transition: all 0.3s;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius);
    text-decoration: none;
    font-weight: 500;
    text-align: center;
    cursor: pointer;
    border: none;
    transition: all 0.2s;
    font-size: 1rem;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
}

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

.btn-secondary:hover {
    background: #475569;
}

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

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

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--bg-secondary) 0%, #e0f2fe 100%);
    padding: 4rem 1rem;
    display: flex;
    align-items: center;
    min-height: 500px;
    position: relative;
    overflow: hidden;
}

.hero-content {
    max-width: var(--max-width);
    margin: 0 auto;
    text-align: center;
    z-index: 2;
}

.hero h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.hero-bg {
    position: absolute;
    top: 0;
    right: 0;
    width: 50%;
    height: 100%;
    opacity: 0.1;
    z-index: 1;
}

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

/* Page Header */
.page-header {
    background: var(--bg-secondary);
    padding: 3rem 1rem;
    text-align: center;
}

.page-header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.page-header p {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

/* Video Grid */
.video-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.video-card {
    background: var(--bg-color);
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    overflow: hidden;
    transition: transform 0.2s, box-shadow 0.2s;
    text-decoration: none;
    color: inherit;
}

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

.video-thumbnail {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.video-info {
    padding: 1.5rem;
}

.video-title {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.video-creator {
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-bottom: 0.5rem;
}

.video-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.875rem;
    color: var(--text-muted);
    margin-bottom: 1rem;
}

.video-category {
    background: var(--primary-color);
    color: white;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 500;
}

.video-description {
    color: var(--text-secondary);
    font-size: 0.875rem;
    line-height: 1.5;
}

/* Categories Grid */
.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
}

.category-card {
    background: var(--bg-color);
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    padding: 2rem;
    text-align: center;
    transition: transform 0.2s, box-shadow 0.2s;
    text-decoration: none;
    color: inherit;
}

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

.category-icon {
    width: 60px;
    height: 60px;
    margin: 0 auto 1rem;
    background: var(--primary-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.5rem;
}

.category-name {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.category-count {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

/* Sections */
.featured-videos,
.categories-preview,
.videos-section,
.categories-section,
.category-videos {
    padding: 4rem 1rem;
}

.featured-videos h2,
.categories-preview h2,
.category-videos h2 {
    font-size: 2rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

.section-footer {
    text-align: center;
    margin-top: 3rem;
}

/* Filters */
.filters-bar {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: var(--radius);
    margin-bottom: 2rem;
    display: flex;
    gap: 2rem;
    align-items: center;
    flex-wrap: wrap;
}

.search-box {
    display: flex;
    gap: 0.5rem;
    flex: 1;
    min-width: 300px;
}

.search-input {
    flex: 1;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    font-size: 1rem;
}

.search-btn {
    padding: 0.75rem 1.5rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    font-weight: 500;
}

.filter-controls {
    display: flex;
    gap: 1rem;
}

.filter-controls select {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    background: white;
    font-size: 1rem;
    min-width: 150px;
}

/* Category Tabs */
.category-filter {
    margin-bottom: 2rem;
}

.category-tabs {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
    flex-wrap: wrap;
    justify-content: center;
}

.category-tab {
    padding: 0.75rem 1.5rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    transition: all 0.2s;
}

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

/* Video Detail */
.video-detail {
    margin: 2rem 0;
}

.video-player {
    background: #000;
    border-radius: var(--radius);
    overflow: hidden;
    margin-bottom: 2rem;
    position: relative;
    padding-bottom: 56.25%;
    height: 0;
}

.video-embed {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
}

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

.video-header h1 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1rem;
    line-height: 1.3;
}

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

.video-main {
    background: var(--bg-color);
}

.video-sidebar {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: var(--radius);
    height: fit-content;
}

.video-sidebar h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.video-sidebar .video-meta {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
}

.video-topics {
    margin-top: 2rem;
}

.topics-list {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1rem;
}

.topic-tag {
    background: var(--accent-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
}

.content-notice {
    background: #fef3c7;
    border: 1px solid #f59e0b;
    border-radius: var(--radius);
    padding: 1rem;
    margin: 2rem 0;
    font-size: 0.875rem;
    color: #92400e;
}

.related-videos {
    margin-top: 4rem;
}

.related-videos h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 2rem;
}

/* No Results */
.no-results {
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-secondary);
}

.no-results h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.video-not-found {
    text-align: center;
    padding: 4rem 2rem;
}

.video-not-found h1 {
    font-size: 2rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

/* Content Sections */
.about-content,
.contact-section,
.legal-content {
    padding: 2rem 1rem 4rem;
}

.content-grid {
    display: grid;
    gap: 3rem;
    max-width: 800px;
    margin: 0 auto;
}

.content-section {
    background: var(--bg-color);
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
}

.content-section h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.content-section h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
    margin-top: 2rem;
    color: var(--text-primary);
}

.content-section ul {
    margin-left: 1.5rem;
    margin-bottom: 1rem;
}

.content-section li {
    margin-bottom: 0.5rem;
    line-height: 1.6;
}

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

.value-item {
    text-align: center;
    padding: 1.5rem;
    background: var(--bg-secondary);
    border-radius: var(--radius);
}

.value-item h3 {
    font-size: 1.125rem;
    margin-bottom: 1rem;
    margin-top: 0;
}

/* Contact */
.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    margin-bottom: 4rem;
}

.contact-info {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: var(--radius);
}

.contact-item {
    margin-bottom: 2rem;
}

.contact-item h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.contact-form {
    background: var(--bg-color);
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    font-size: 1rem;
    font-family: inherit;
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

.checkbox-label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
}

.form-message {
    margin-top: 1rem;
    padding: 1rem;
    border-radius: var(--radius);
    font-weight: 500;
}

.form-message.success {
    background: #d1fae5;
    color: #065f46;
    border: 1px solid #10b981;
}

.form-message.error {
    background: #fee2e2;
    color: #991b1b;
    border: 1px solid #ef4444;
}

.faq-section {
    margin-top: 4rem;
}

.faq-section h2 {
    text-align: center;
    margin-bottom: 2rem;
}

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

.faq-item {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: var(--radius);
}

.faq-item h3 {
    font-size: 1.125rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

/* Legal Content */
.disclaimer-highlight {
    background: #fef3c7;
    border-left: 4px solid var(--accent-color);
}

.highlight-text {
    font-size: 1.125rem;
    font-weight: 600;
    color: #92400e;
    margin-bottom: 1rem;
}

/* Footer */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 3rem 1rem 1rem;
}

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

.footer-section h4 {
    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: color 0.2s;
}

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

.footer-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
    font-weight: 600;
    font-size: 1.25rem;
}

.footer-bottom {
    border-top: 1px solid #475569;
    padding-top: 2rem;
    text-align: center;
    color: #cbd5e1;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--bg-color);
        border-top: 1px solid var(--border-color);
        flex-direction: column;
        padding: 1rem;
        gap: 1rem;
    }

    .nav-menu.active {
        display: flex;
    }

    .nav-toggle {
        display: flex;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .hero p {
        font-size: 1rem;
    }

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

    .video-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .filters-bar {
        flex-direction: column;
        align-items: stretch;
    }

    .search-box {
        min-width: auto;
    }

    .filter-controls {
        flex-direction: column;
    }

    .filter-controls select {
        min-width: auto;
    }

    .video-details {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .contact-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .category-tabs {
        justify-content: flex-start;
    }

    .hero-bg {
        display: none;
    }

    .page-header h1 {
        font-size: 2rem;
    }

    .content-section {
        padding: 1.5rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 0.5rem;
    }

    .hero {
        padding: 2rem 1rem;
    }

    .hero h1 {
        font-size: 1.75rem;
    }

    .featured-videos,
    .categories-preview,
    .videos-section,
    .categories-section,
    .category-videos {
        padding: 2rem 1rem;
    }

    .video-card {
        margin: 0 0.5rem;
    }

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

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

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

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