/* Reset and Base Styles */
* {
    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;
}

img {
    max-width: 100%;
    height: auto;
}

a {
    color: #1976d2;
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

.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 {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 20px;
    max-width: 1200px;
    margin: 0 auto;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 600;
    font-size: 1.2rem;
    color: #1976d2;
}

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

.nav-link {
    color: #333;
    font-weight: 500;
    padding: 0.5rem 0;
    transition: color 0.3s;
}

.nav-link:hover,
.nav-link.active {
    color: #1976d2;
    text-decoration: none;
}

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

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

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #1976d2 0%, #1565c0 100%);
    color: white;
    padding: 4rem 0;
    text-align: center;
}

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

.hero-content p {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 24px;
    border-radius: 6px;
    font-weight: 600;
    text-align: center;
    transition: all 0.3s;
    border: none;
    cursor: pointer;
    text-decoration: none;
}

.btn-primary {
    background: #fff;
    color: #1976d2;
}

.btn-primary:hover {
    background: #f5f5f5;
    text-decoration: none;
}

/* Main Content */
.main {
    min-height: calc(100vh - 200px);
    padding: 2rem 0;
}

.page-header {
    text-align: center;
    margin-bottom: 3rem;
}

.page-header h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: #333;
}

.page-header p {
    font-size: 1.1rem;
    color: #666;
}

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

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

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

.video-thumbnail {
    position: relative;
    padding-bottom: 56.25%; /* 16:9 aspect ratio */
    height: 0;
    overflow: hidden;
}

.video-thumbnail img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.video-info {
    padding: 1.5rem;
}

.video-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #333;
    line-height: 1.4;
}

.video-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
    color: #666;
}

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

.video-category {
    display: inline-block;
    background: #e3f2fd;
    color: #1976d2;
    padding: 4px 8px;
    border-radius: 4px;
    font-size: 0.8rem;
    font-weight: 500;
}

/* Filters */
.filters {
    background: #f8f9fa;
    padding: 2rem;
    border-radius: 12px;
    margin-bottom: 3rem;
}

.search-box {
    margin-bottom: 1rem;
}

.search-box input {
    width: 100%;
    padding: 12px;
    border: 2px solid #ddd;
    border-radius: 6px;
    font-size: 1rem;
}

.search-box input:focus {
    outline: none;
    border-color: #1976d2;
}

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

.filter-controls select {
    padding: 10px;
    border: 2px solid #ddd;
    border-radius: 6px;
    font-size: 1rem;
    background: white;
}

/* Categories */
.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.category-card {
    background: #f8f9fa;
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    transition: all 0.3s;
    text-decoration: none;
    color: #333;
}

.category-card:hover {
    background: #e3f2fd;
    transform: translateY(-3px);
    text-decoration: none;
}

.category-card h3 {
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
    color: #1976d2;
}

/* Category Tabs */
.category-tabs {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.tab-btn {
    padding: 10px 20px;
    background: #f8f9fa;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s;
}

.tab-btn.active,
.tab-btn:hover {
    background: #1976d2;
    color: white;
}

/* Video Detail */
.video-detail {
    max-width: 800px;
    margin: 0 auto;
}

.video-player {
    position: relative;
    padding-bottom: 56.25%;
    height: 0;
    overflow: hidden;
    margin-bottom: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
}

.video-player iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border-radius: 12px;
}

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

.video-meta-detail {
    display: flex;
    gap: 2rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.meta-item {
    color: #666;
}

.meta-item strong {
    color: #333;
}

.video-description-full {
    line-height: 1.8;
    margin-bottom: 2rem;
}

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

.topic-tag {
    display: inline-block;
    background: #e3f2fd;
    color: #1976d2;
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 0.9rem;
    margin: 4px;
}

.content-notice {
    background: #fff3cd;
    border: 1px solid #ffeaa7;
    border-radius: 6px;
    padding: 1rem;
    margin-bottom: 2rem;
}

/* Featured Section */
.featured {
    padding: 4rem 0;
    background: #f8f9fa;
}

.featured h2 {
    text-align: center;
    margin-bottom: 3rem;
    font-size: 2.2rem;
}

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

.categories-preview h2 {
    text-align: center;
    margin-bottom: 3rem;
    font-size: 2.2rem;
}

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

.contact-info h2,
.contact-form h2 {
    margin-bottom: 2rem;
}

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

.contact-item h3 {
    color: #1976d2;
    margin-bottom: 0.5rem;
}

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

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

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 12px;
    border: 2px solid #ddd;
    border-radius: 6px;
    font-size: 1rem;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: #1976d2;
}

/* Legal Content */
.legal-content {
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.8;
}

.legal-content h2 {
    margin: 2rem 0 1rem 0;
    color: #1976d2;
}

.legal-content ul {
    margin: 1rem 0;
    padding-left: 2rem;
}

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

/* Content Sections */
.content-section {
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.8;
}

.content-section h2 {
    margin: 2rem 0 1rem 0;
    color: #1976d2;
}

.content-section ul {
    margin: 1rem 0;
    padding-left: 2rem;
}

/* Footer */
.footer {
    background: #333;
    color: white;
    padding: 3rem 0 1rem 0;
    margin-top: 4rem;
}

.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;
    color: #1976d2;
}

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

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

.footer-section a {
    color: #ccc;
}

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

.footer-bottom {
    border-top: 1px solid #555;
    padding-top: 2rem;
    text-align: center;
    color: #ccc;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background: white;
        flex-direction: column;
        padding: 1rem;
        box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    }

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

    .nav-toggle {
        display: flex;
    }

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

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

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

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

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

    .category-tabs {
        justify-content: center;
    }

    .tab-btn {
        flex: 1;
        min-width: 120px;
    }

    .video-meta-detail {
        flex-direction: column;
        gap: 1rem;
    }
}

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

    .nav-container {
        padding: 1rem 15px;
    }

    .hero {
        padding: 2rem 0;
    }

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

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

    .filters {
        padding: 1.5rem;
    }

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

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