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

:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-color: #64748b;
    --background-color: #ffffff;
    --surface-color: #f8fafc;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 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);
    --border-radius: 8px;
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

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

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

.logo {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 700;
    font-size: 1.25rem;
}

.logo-img {
    width: 32px;
    height: 32px;
    margin-right: 0.5rem;
}

.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;
    padding: 0.5rem;
}

.nav-toggle span {
    width: 20px;
    height: 2px;
    background: var(--text-primary);
    margin: 2px 0;
    transition: 0.3s;
}

/* Hero */
.hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, #3b82f6 100%);
    color: white;
    padding: 4rem 1rem;
    display: flex;
    align-items: center;
    min-height: 500px;
}

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

.hero-title {
    font-size: 3rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 1rem;
}

.hero-subtitle {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

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

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 600;
    transition: all 0.2s;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

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

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

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

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

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

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

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

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

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

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

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

.video-info {
    padding: 1.5rem;
}

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

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

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

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

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

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

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

.category-card h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.category-card p {
    color: var(--text-secondary);
}

/* Search and Filters */
.search-section {
    background: var(--surface-color);
    padding: 2rem 0;
}

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

.search-form {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
}

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

.search-input:focus {
    outline: none;
    border-color: var(--primary-color);
}

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

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

/* Video Detail */
.video-detail {
    max-width: 1000px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

.video-player {
    width: 100%;
    aspect-ratio: 16/9;
    background: #000;
    border-radius: var(--border-radius);
    margin-bottom: 2rem;
}

.video-embed {
    width: 100%;
    height: 100%;
    border: none;
    border-radius: var(--border-radius);
}

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

.video-details-meta {
    display: flex;
    gap: 2rem;
    margin-bottom: 2rem;
    color: var(--text-secondary);
}

.video-description-full {
    line-height: 1.6;
    margin-bottom: 2rem;
}

.video-topics {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 2rem;
}

.topic-tag {
    background: var(--surface-color);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.content-disclaimer {
    background: var(--surface-color);
    padding: 1rem;
    border-radius: var(--border-radius);
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-top: 2rem;
}

/* Footer */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 3rem 0 1rem;
}

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

.footer-section h3,
.footer-section h4 {
    margin-bottom: 1rem;
}

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

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

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color 0.2s;
}

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

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
}

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

.form-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

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

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

.form-input:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

/* Responsive */
@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;
    }
    
    .video-grid {
        grid-template-columns: 1fr;
    }
    
    .search-form {
        flex-direction: column;
    }
    
    .filters {
        justify-content: flex-start;
    }
    
    .video-details-meta {
        flex-direction: column;
        gap: 0.5rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 0.5rem;
    }
    
    .hero {
        padding: 2rem 1rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .video-info {
        padding: 1rem;
    }
}

/* Print styles */
@media print {
    .header,
    .footer,
    .nav-toggle {
        display: none;
    }
    
    .main {
        margin-top: 0;
    }
    
    .video-card,
    .category-card {
        break-inside: avoid;
    }
}