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

:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary-color: #f8fafc;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;
    --white: #ffffff;
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-400: #94a3b8;
    --gray-500: #64748b;
    --gray-600: #475569;
    --gray-700: #334155;
    --gray-800: #1e293b;
    --gray-900: #0f172a;
    --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: 0.5rem;
    --border-radius-lg: 0.75rem;
    --max-width: 1200px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--white);
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1rem;
}

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

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

.nav-brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    text-decoration: none;
    color: var(--text-primary);
}

.logo,
.footer-logo {
    width: 32px;
    height: 32px;
}

.brand-name {
    font-size: 1.25rem;
    font-weight: 600;
}

.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: 24px;
    height: 2px;
    background: var(--text-primary);
    margin: 2px 0;
    transition: 0.3s;
}

/* Hero Section */
.hero {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
    padding: 4rem 1rem;
    max-width: var(--max-width);
    margin: 0 auto;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    line-height: 1.2;
}

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

.hero-cta {
    display: inline-block;
    background: var(--primary-color);
    color: var(--white);
    padding: 1rem 2rem;
    text-decoration: none;
    border-radius: var(--border-radius);
    font-weight: 600;
    transition: background-color 0.2s;
}

.hero-cta:hover {
    background: var(--primary-dark);
}

.hero-image img {
    width: 100%;
    height: auto;
    border-radius: var(--border-radius-lg);
}

/* Sections */
.featured-section,
.categories-preview {
    padding: 4rem 0;
}

.categories-preview {
    background: var(--gray-50);
}

.section-title {
    font-size: 2.25rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
}

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

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

.video-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.video-thumbnail {
    position: relative;
    aspect-ratio: 16/9;
    overflow: hidden;
}

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

.video-duration {
    position: absolute;
    bottom: 0.5rem;
    right: 0.5rem;
    background: rgba(0, 0, 0, 0.8);
    color: var(--white);
    padding: 0.25rem 0.5rem;
    border-radius: 0.25rem;
    font-size: 0.875rem;
    font-weight: 500;
}

.video-info {
    padding: 1.5rem;
}

.video-title {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.video-channel {
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-bottom: 0.75rem;
}

.video-description {
    color: var(--text-secondary);
    font-size: 0.875rem;
    line-height: 1.5;
    margin-bottom: 1rem;
}

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

.video-category {
    background: var(--gray-100);
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 500;
}

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

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

.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);
}

/* Section Footer */
.section-footer {
    text-align: center;
}

.view-all-btn {
    display: inline-block;
    background: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
    padding: 0.75rem 2rem;
    text-decoration: none;
    border-radius: var(--border-radius);
    font-weight: 600;
    transition: background-color 0.2s, color 0.2s;
}

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

/* Search and Filter */
.search-section {
    background: var(--gray-50);
    padding: 2rem 0;
}

.search-form {
    display: flex;
    gap: 1rem;
    max-width: 800px;
    margin: 0 auto;
    flex-wrap: wrap;
}

.search-input,
.filter-select {
    flex: 1;
    min-width: 200px;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
}

.search-btn {
    background: var(--primary-color);
    color: var(--white);
    border: none;
    padding: 0.75rem 2rem;
    border-radius: var(--border-radius);
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

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

/* Video Detail */
.video-detail {
    padding: 2rem 0;
}

.video-player {
    aspect-ratio: 16/9;
    margin-bottom: 2rem;
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
}

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

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

.video-detail-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.video-detail-meta {
    display: flex;
    gap: 2rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.video-detail-description {
    font-size: 1.125rem;
    line-height: 1.7;
    margin-bottom: 2rem;
}

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

.topic-tag {
    background: var(--gray-100);
    padding: 0.5rem 1rem;
    border-radius: 1rem;
    font-size: 0.875rem;
    font-weight: 500;
}

.content-disclaimer {
    background: var(--gray-50);
    padding: 1rem;
    border-radius: var(--border-radius);
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-top: 2rem;
}

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

.form-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.form-input,
.form-textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: border-color 0.2s;
}

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

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

.form-btn {
    background: var(--primary-color);
    color: var(--white);
    border: none;
    padding: 1rem 2rem;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

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

/* Content Pages */
.page-header {
    text-align: center;
    padding: 4rem 0 2rem;
}

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

.page-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
}

.page-content {
    padding: 2rem 0;
    max-width: 800px;
    margin: 0 auto;
}

.page-content h2 {
    font-size: 1.75rem;
    margin: 2rem 0 1rem;
}

.page-content h3 {
    font-size: 1.5rem;
    margin: 1.5rem 0 0.75rem;
}

.page-content p {
    margin-bottom: 1rem;
    line-height: 1.7;
}

.page-content ul,
.page-content ol {
    margin: 1rem 0 1rem 2rem;
}

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

/* Contact Info */
.contact-info {
    background: var(--gray-50);
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    margin-bottom: 2rem;
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.contact-item:last-child {
    margin-bottom: 0;
}

.contact-icon {
    width: 24px;
    height: 24px;
    margin-top: 0.125rem;
}

.contact-details h3 {
    font-size: 1.125rem;
    margin-bottom: 0.25rem;
}

.contact-details p {
    color: var(--text-secondary);
    margin: 0;
}

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

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

/* Footer */
.footer {
    background: var(--gray-900);
    color: var(--white);
    padding: 3rem 0 1rem;
    margin-top: 4rem;
}

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

.footer-brand p {
    color: var(--gray-400);
    margin-top: 1rem;
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
}

.footer-column h4 {
    margin-bottom: 1rem;
    font-size: 1.125rem;
}

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

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

.footer-column a {
    color: var(--gray-400);
    text-decoration: none;
    transition: color 0.2s;
}

.footer-column a:hover {
    color: var(--white);
}

.footer-bottom {
    border-top: 1px solid var(--gray-700);
    padding-top: 1rem;
    text-align: center;
    color: var(--gray-400);
}

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

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

    .nav-toggle {
        display: flex;
    }

    .hero {
        grid-template-columns: 1fr;
        gap: 2rem;
        padding: 2rem 1rem;
        text-align: center;
    }

    .hero-title {
        font-size: 2rem;
    }

    .page-title {
        font-size: 2rem;
    }

    .section-title {
        font-size: 1.75rem;
    }

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

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

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

    .video-detail-meta {
        flex-direction: column;
        gap: 0.5rem;
    }

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

@media (max-width: 480px) {
    .container {
        padding: 0 0.75rem;
    }

    .hero {
        padding: 1.5rem 0.75rem;
    }

    .featured-section,
    .categories-preview {
        padding: 2rem 0;
    }

    .page-header {
        padding: 2rem 0 1rem;
    }

    .hero-title {
        font-size: 1.75rem;
    }

    .page-title {
        font-size: 1.75rem;
    }

    .section-title {
        font-size: 1.5rem;
    }
}