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

:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-color: #64748b;
    --secondary-hover: #475569;
    --accent-color: #f59e0b;
    --background-color: #ffffff;
    --surface-color: #f8fafc;
    --border-color: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --success-color: #10b981;
    --error-color: #ef4444;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --border-radius: 8px;
    --border-radius-lg: 12px;
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    --transition: all 0.2s ease;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--background-color);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* Header & Navigation */
.header {
    background: var(--background-color);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
    height: 64px;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 600;
    font-size: 1.125rem;
}

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

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

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

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--primary-color);
}

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

.nav-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    margin: 2px 0;
    transition: var(--transition);
}

/* Main Content */
.main {
    min-height: calc(100vh - 64px);
    padding-bottom: 2rem;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--surface-color) 0%, var(--background-color) 100%);
    padding: 4rem 0;
    display: flex;
    align-items: center;
    min-height: 500px;
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1rem;
    line-height: 1.1;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    line-height: 1.5;
}

.hero-bg img {
    width: 100%;
    height: auto;
    max-width: 500px;
}

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

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

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: var(--surface-color);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background: var(--border-color);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

/* Sections */
.section-title {
    font-size: 2rem;
    font-weight: 600;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

.featured-section,
.categories-section {
    padding: 4rem 0;
}

.categories-section {
    background: var(--surface-color);
}

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

.video-card {
    background: var(--background-color);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-md);
    overflow: hidden;
    transition: var(--transition);
    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;
    background: var(--surface-color);
}

.video-info {
    padding: 1.5rem;
}

.video-title {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    line-height: 1.4;
}

.video-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin-bottom: 1rem;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

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

.video-topics {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.topic-tag {
    background: var(--surface-color);
    color: var(--text-secondary);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 500;
}

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

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

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

.category-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.category-count {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Page Header */
.page-header {
    text-align: center;
    padding: 3rem 0;
}

.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);
    max-width: 600px;
    margin: 0 auto;
}

/* Filters */
.filters-section {
    background: var(--surface-color);
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    margin-bottom: 2rem;
}

.search-bar {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

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

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

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

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

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

.filter-select {
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    background: var(--background-color);
    font-size: 0.9rem;
}

.results-info {
    margin-bottom: 2rem;
    color: var(--text-secondary);
    font-weight: 500;
}

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

.no-results h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

/* Video Detail Page */
.breadcrumb {
    padding: 1rem 0;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.breadcrumb a {
    color: var(--primary-color);
    text-decoration: none;
}

.breadcrumb a:hover {
    text-decoration: underline;
}

.video-detail {
    max-width: 1000px;
    margin: 0 auto;
}

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

.video-embed {
    position: relative;
    width: 100%;
    height: 0;
    padding-bottom: 56.25%;
    background: var(--surface-color);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
}

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

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

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

.video-info h1 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.content-notice {
    background: var(--surface-color);
    padding: 1rem;
    border-radius: var(--border-radius);
    margin: 2rem 0;
    border-left: 4px solid var(--accent-color);
}

.related-videos {
    margin-top: 3rem;
}

.related-videos h3 {
    font-size: 1.5rem;
    margin-bottom: 2rem;
    color: var(--text-primary);
}

/* Categories Page */
.categories-overview {
    margin-bottom: 4rem;
}

.category-sections {
    margin-top: 3rem;
}

.category-section {
    margin-bottom: 4rem;
}

.category-section h2 {
    font-size: 1.75rem;
    margin-bottom: 2rem;
    color: var(--text-primary);
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
}

/* Forms */
.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    margin-top: 2rem;
}

.contact-form {
    background: var(--surface-color);
    padding: 2rem;
    border-radius: var(--border-radius-lg);
}

.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(--border-radius);
    font-size: 1rem;
    background: var(--background-color);
    transition: var(--transition);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgb(37 99 235 / 0.1);
}

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

.form-message.success {
    background: rgb(16 185 129 / 0.1);
    color: var(--success-color);
    border: 1px solid rgb(16 185 129 / 0.2);
}

.form-message.error {
    background: rgb(239 68 68 / 0.1);
    color: var(--error-color);
    border: 1px solid rgb(239 68 68 / 0.2);
}

.contact-methods {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.contact-method h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

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

.contact-method a {
    color: var(--primary-color);
    text-decoration: none;
}

.contact-method a:hover {
    text-decoration: underline;
}

/* FAQ */
.faq-section {
    grid-column: 1 / -1;
    margin-top: 3rem;
}

.faq-item {
    margin-bottom: 2rem;
    padding: 1.5rem;
    background: var(--surface-color);
    border-radius: var(--border-radius);
}

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

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

/* Legal Pages */
.legal-content {
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.7;
}

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

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

.legal-section h3 {
    font-size: 1.25rem;
    margin: 1.5rem 0 0.5rem;
    color: var(--text-primary);
}

.legal-section ul {
    margin: 1rem 0 1rem 2rem;
}

.legal-section li {
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

.contact-info {
    background: var(--surface-color);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    margin: 1rem 0;
}

.category-list {
    list-style: none;
    margin: 1rem 0;
}

.category-list li {
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--border-color);
}

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

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.feature-card {
    background: var(--surface-color);
    padding: 2rem;
    border-radius: var(--border-radius);
}

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

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

/* Footer */
.footer {
    background: var(--text-primary);
    color: var(--background-color);
    margin-top: 4rem;
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 3rem 1rem 1rem;
}

.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;
    margin-bottom: 1rem;
    color: var(--background-color);
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
    font-weight: 600;
    font-size: 1.125rem;
}

.footer-links {
    list-style: none;
}

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

.footer-links a {
    color: var(--text-muted);
    text-decoration: none;
    transition: var(--transition);
}

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

.footer-bottom {
    border-top: 1px solid var(--secondary-color);
    padding-top: 1rem;
    text-align: center;
    color: var(--text-muted);
    font-size: 0.9rem;
}

.disclaimer-text {
    margin-top: 0.5rem;
    font-size: 0.8rem;
    font-style: italic;
}

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

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1.125rem;
    }
    
    .video-grid {
        grid-template-columns: 1fr;
    }
    
    .categories-grid {
        grid-template-columns: 1fr;
    }
    
    .contact-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .filters {
        flex-direction: column;
        align-items: stretch;
    }
    
    .search-bar {
        flex-direction: column;
    }
    
    .page-header h1 {
        font-size: 2rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 0.5rem;
    }
    
    .hero {
        padding: 2rem 0;
    }
    
    .hero-title {
        font-size: 1.75rem;
    }
    
    .featured-section,
    .categories-section {
        padding: 2rem 0;
    }
    
    .page-header {
        padding: 2rem 0;
    }
    
    .video-info {
        padding: 1rem;
    }
    
    .contact-form {
        padding: 1rem;
    }
}