* {
    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: #ffffff;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

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

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.logo {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: #333;
    font-weight: bold;
    font-size: 1.25rem;
}

.logo img {
    width: 32px;
    height: 32px;
    margin-right: 10px;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 30px;
}

.nav-menu a {
    text-decoration: none;
    color: #666;
    font-weight: 500;
    transition: color 0.3s ease;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: #2196F3;
}

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

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: #333;
    margin: 3px 0;
    transition: 0.3s;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 100px 0;
    text-align: center;
}

.hero-content h1 {
    font-size: 3rem;
    margin-bottom: 20px;
    font-weight: 700;
}

.hero-content p {
    font-size: 1.25rem;
    margin-bottom: 30px;
    opacity: 0.9;
}

.btn {
    display: inline-block;
    padding: 12px 30px;
    text-decoration: none;
    border-radius: 5px;
    font-weight: 600;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn-primary {
    background: #2196F3;
    color: white;
}

.btn-primary:hover {
    background: #1976D2;
    transform: translateY(-2px);
}

/* Video Grid */
.featured,
.videos-section,
.categories-preview {
    padding: 80px 0;
}

.featured h2,
.videos-section h2,
.categories-preview h2 {
    font-size: 2.5rem;
    margin-bottom: 50px;
    text-align: center;
    color: #333;
}

.video-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 30px;
}

.video-card {
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

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

.video-card a {
    text-decoration: none;
    color: inherit;
    display: block;
}

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

.video-info {
    padding: 20px;
}

.video-info h3 {
    font-size: 1.25rem;
    margin-bottom: 10px;
    color: #333;
    line-height: 1.3;
}

.video-channel {
    color: #666;
    margin-bottom: 15px;
    font-size: 0.9rem;
}

.video-meta {
    display: flex;
    gap: 15px;
    font-size: 0.85rem;
    color: #888;
}

.video-meta span {
    display: flex;
    align-items: center;
}

.category {
    background: #E3F2FD;
    color: #1976D2;
    padding: 4px 8px;
    border-radius: 4px;
    font-weight: 500;
}

/* Categories */
.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 25px;
}

.category-card {
    background: white;
    padding: 30px;
    border-radius: 12px;
    text-decoration: none;
    color: #333;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    text-align: center;
}

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

.category-card h3 {
    font-size: 1.5rem;
    margin-bottom: 10px;
    color: #2196F3;
}

.category-card p {
    color: #666;
}

/* Search and Filters */
.search-section {
    background: #f8f9fa;
    padding: 40px 0;
}

.search-container {
    display: flex;
    gap: 20px;
    margin-bottom: 30px;
    flex-wrap: wrap;
}

.search-input {
    flex: 1;
    min-width: 300px;
    padding: 12px 20px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 1rem;
}

.search-input:focus {
    outline: none;
    border-color: #2196F3;
}

.filter-select {
    padding: 12px 20px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 1rem;
    background: white;
}

.filter-select:focus {
    outline: none;
    border-color: #2196F3;
}

/* Video Detail Page */
.video-detail {
    padding: 40px 0;
}

.video-player {
    background: #000;
    border-radius: 12px;
    overflow: hidden;
    margin-bottom: 30px;
    aspect-ratio: 16/9;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.2rem;
}

.video-details h1 {
    font-size: 2rem;
    margin-bottom: 15px;
    color: #333;
}

.video-metadata {
    display: flex;
    gap: 20px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.video-metadata span {
    color: #666;
    font-size: 0.9rem;
}

.video-description {
    background: #f8f9fa;
    padding: 25px;
    border-radius: 8px;
    margin-bottom: 30px;
}

.video-description h3 {
    margin-bottom: 15px;
    color: #333;
}

.video-description p {
    color: #666;
    line-height: 1.7;
}

.video-topics {
    margin-top: 20px;
}

.topic-tag {
    display: inline-block;
    background: #E3F2FD;
    color: #1976D2;
    padding: 5px 12px;
    border-radius: 20px;
    font-size: 0.85rem;
    margin: 5px 5px 5px 0;
}

/* Footer */
.footer {
    background: #333;
    color: white;
    padding: 50px 0 20px;
    margin-top: 80px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    margin-bottom: 30px;
}

.footer-section h4 {
    margin-bottom: 20px;
    color: #2196F3;
}

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

.footer-section ul li {
    margin-bottom: 10px;
}

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

.footer-section a:hover {
    color: #2196F3;
}

.footer-bottom {
    border-top: 1px solid #555;
    padding-top: 20px;
    text-align: center;
    color: #ccc;
}

/* Content Pages */
.content-page {
    padding: 40px 0;
    min-height: 60vh;
}

.content-page h1 {
    font-size: 2.5rem;
    margin-bottom: 30px;
    color: #333;
}

.content-page h2 {
    font-size: 1.8rem;
    margin: 30px 0 15px;
    color: #333;
}

.content-page p {
    margin-bottom: 20px;
    line-height: 1.7;
    color: #666;
}

.content-page ul {
    margin: 20px 0;
    padding-left: 30px;
}

.content-page li {
    margin-bottom: 10px;
    color: #666;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: 0 10px 27px rgba(0,0,0,0.05);
        padding: 20px 0;
        gap: 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-menu li {
        margin: 15px 0;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }

    .nav-toggle.active span:nth-child(1) {
        transform: translateY(8px) rotate(45deg);
    }

    .nav-toggle.active span:nth-child(3) {
        transform: translateY(-8px) rotate(-45deg);
    }

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

    .hero-content p {
        font-size: 1.1rem;
    }

    .video-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .search-container {
        flex-direction: column;
    }

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

    .video-metadata {
        flex-direction: column;
        gap: 10px;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: 30px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }

    .nav-container {
        padding: 0 15px;
    }

    .hero {
        padding: 60px 0;
    }

    .hero-content h1 {
        font-size: 1.8rem;
    }

    .featured,
    .videos-section,
    .categories-preview {
        padding: 50px 0;
    }

    .featured h2,
    .videos-section h2,
    .categories-preview h2 {
        font-size: 2rem;
        margin-bottom: 30px;
    }
}

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

.mb-20 {
    margin-bottom: 20px;
}

.mb-30 {
    margin-bottom: 30px;
}

.hidden {
    display: none;
}

.fade-in {
    opacity: 0;
    animation: fadeIn 0.5s ease-in forwards;
}

@keyframes fadeIn {
    to {
        opacity: 1;
    }
}