* {
    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: #333;
    background-color: #fff;
}

.header {
    background: #fff;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo {
    width: 40px;
    height: 40px;
}

.brand-name {
    font-size: 1.5rem;
    font-weight: 700;
    color: #e74c3c;
}

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

.nav-link {
    text-decoration: none;
    color: #333;
    font-weight: 500;
    transition: color 0.3s;
}

.nav-link:hover,
.nav-link.active {
    color: #e74c3c;
}

.main {
    min-height: calc(100vh - 200px);
}

.hero {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
    padding: 4rem 2rem;
}

.hero-content h1 {
    font-size: 3rem;
    font-weight: 800;
    color: #2c3e50;
    margin-bottom: 1rem;
}

.hero-content p {
    font-size: 1.2rem;
    color: #666;
    margin-bottom: 2rem;
}

.cta-button {
    display: inline-block;
    background: #e74c3c;
    color: white;
    padding: 1rem 2rem;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
    transition: background 0.3s;
}

.cta-button:hover {
    background: #c0392b;
}

.hero-image img {
    width: 100%;
    height: auto;
}

.featured-section,
.videos-section,
.categories-preview,
.categories-grid {
    max-width: 1200px;
    margin: 0 auto;
    padding: 4rem 2rem;
}

.featured-section h2,
.videos-section h2,
.categories-preview h2 {
    font-size: 2.5rem;
    font-weight: 700;
    color: #2c3e50;
    margin-bottom: 2rem;
    text-align: center;
}

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

.video-card {
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    transition: transform 0.3s, box-shadow 0.3s;
    text-decoration: none;
    color: inherit;
}

.video-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 30px rgba(0,0,0,0.15);
}

.video-thumbnail {
    position: relative;
    width: 100%;
    height: 200px;
    overflow: hidden;
}

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

.video-duration {
    position: absolute;
    bottom: 10px;
    right: 10px;
    background: rgba(0,0,0,0.8);
    color: white;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.8rem;
}

.video-info {
    padding: 1.5rem;
}

.video-title {
    font-size: 1.2rem;
    font-weight: 600;
    color: #2c3e50;
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.video-creator {
    color: #666;
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

.video-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.video-category {
    background: #e74c3c;
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 500;
}

.video-views {
    color: #666;
    font-size: 0.8rem;
}

.video-description {
    color: #666;
    font-size: 0.9rem;
    line-height: 1.5;
}

.category-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.category-card {
    background: linear-gradient(135deg, #e74c3c, #c0392b);
    color: white;
    padding: 2rem;
    border-radius: 12px;
    text-decoration: none;
    transition: transform 0.3s;
}

.category-card:hover {
    transform: translateY(-3px);
}

.category-card h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.category-card p {
    opacity: 0.9;
}

.page-header {
    background: linear-gradient(135deg, #2c3e50, #34495e);
    color: white;
    text-align: center;
    padding: 4rem 2rem;
}

.page-header h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.page-header p {
    font-size: 1.2rem;
    opacity: 0.9;
}

.filters-section {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

.search-filter {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.search-input,
.category-filter {
    padding: 0.75rem 1rem;
    border: 2px solid #ddd;
    border-radius: 8px;
    font-size: 1rem;
    min-width: 200px;
}

.search-input:focus,
.category-filter:focus {
    outline: none;
    border-color: #e74c3c;
}

.content-section {
    max-width: 1200px;
    margin: 0 auto;
    padding: 4rem 2rem;
}

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

.content-container h2 {
    font-size: 2rem;
    color: #2c3e50;
    margin: 2rem 0 1rem 0;
}

.content-container h3 {
    font-size: 1.5rem;
    color: #34495e;
    margin: 1.5rem 0 1rem 0;
}

.content-container p {
    margin-bottom: 1rem;
    line-height: 1.8;
}

.content-container ul {
    margin: 1rem 0 1rem 2rem;
}

.content-container li {
    margin-bottom: 0.5rem;
}

.video-detail-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

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

.video-player {
    background: #000;
    border-radius: 12px;
    overflow: hidden;
    aspect-ratio: 16/9;
}

.video-embed {
    width: 100%;
    height: 100%;
    border: none;
}

.video-details h1 {
    font-size: 2rem;
    color: #2c3e50;
    margin-bottom: 1rem;
}

.video-meta-detail {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.meta-item {
    background: #f8f9fa;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    font-size: 0.9rem;
}

.video-description-full {
    line-height: 1.8;
    color: #555;
}

.video-topics {
    margin-top: 1.5rem;
}

.topic-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 0.5rem;
}

.topic-tag {
    background: #e74c3c;
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.8rem;
}

.content-notice {
    background: #f8f9fa;
    border: 1px solid #dee2e6;
    border-radius: 8px;
    padding: 1rem;
    margin-top: 1.5rem;
    font-size: 0.9rem;
    color: #666;
}

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

.category-section h2 {
    font-size: 2rem;
    color: #2c3e50;
    margin-bottom: 0.5rem;
}

.category-section p {
    color: #666;
    margin-bottom: 2rem;
}

.contact-section {
    max-width: 1200px;
    margin: 0 auto;
    padding: 4rem 2rem;
}

.contact-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
}

.contact-info h2,
.contact-form-container h2 {
    font-size: 2rem;
    color: #2c3e50;
    margin-bottom: 1.5rem;
}

.contact-details {
    margin-top: 2rem;
}

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

.contact-item h3 {
    font-size: 1.2rem;
    color: #34495e;
    margin-bottom: 0.5rem;
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
}

.form-group label {
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #2c3e50;
}

.form-group input,
.form-group textarea {
    padding: 0.75rem;
    border: 2px solid #ddd;
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: #e74c3c;
}

.submit-button {
    background: #e74c3c;
    color: white;
    padding: 1rem 2rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.3s;
}

.submit-button:hover {
    background: #c0392b;
}

.faq-section {
    background: #f8f9fa;
    padding: 4rem 2rem;
}

.faq-item {
    background: white;
    border-radius: 8px;
    padding: 2rem;
    margin-bottom: 1.5rem;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.faq-item h3 {
    color: #2c3e50;
    margin-bottom: 1rem;
}

.footer {
    background: #2c3e50;
    color: white;
    padding: 3rem 0 1rem 0;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    padding: 0 2rem;
}

.footer-section h3 {
    margin-bottom: 1rem;
    color: #e74c3c;
}

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

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

.footer-section a {
    color: #bdc3c7;
    text-decoration: none;
    transition: color 0.3s;
}

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

.footer-bottom {
    max-width: 1200px;
    margin: 2rem auto 0;
    padding: 2rem;
    border-top: 1px solid #34495e;
    text-align: center;
    color: #bdc3c7;
}

.related-videos {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

.related-videos h2 {
    font-size: 2rem;
    color: #2c3e50;
    margin-bottom: 2rem;
}

@media (max-width: 768px) {
    .nav {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-menu {
        gap: 1rem;
    }
    
    .hero {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-content h1 {
        font-size: 2rem;
    }
    
    .video-grid {
        grid-template-columns: 1fr;
    }
    
    .video-detail {
        grid-template-columns: 1fr;
    }
    
    .contact-container {
        grid-template-columns: 1fr;
    }
    
    .search-filter {
        flex-direction: column;
        align-items: center;
    }
    
    .page-header h1 {
        font-size: 2rem;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 2rem 1rem;
    }
    
    .featured-section,
    .videos-section,
    .categories-preview,
    .content-section,
    .contact-section {
        padding: 2rem 1rem;
    }
    
    .page-header {
        padding: 2rem 1rem;
    }
}