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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
    line-height: 1.6;
    color: #1f2937;
    background: #f9fafb;
}

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

.site-header {
    background: #fff;
    border-bottom: 1px solid #e5e7eb;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 0;
}

.logo {
    display: flex;
    flex-direction: column;
}

.logo a {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: #1f2937;
}

.logo-icon {
    font-size: 32px;
    margin-right: 10px;
}

.logo-text {
    font-size: 20px;
    font-weight: 700;
    color: #1f2937;
}

.tagline {
    font-size: 12px;
    color: #6b7280;
    margin-left: 42px;
    margin-top: -5px;
}

.main-nav {
    display: flex;
    gap: 30px;
}

.nav-item {
    color: #4b5563;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

.nav-item:hover {
    color: #3b82f6;
}

.breadcrumb {
    padding: 15px 0;
    font-size: 14px;
    color: #6b7280;
}

.breadcrumb a {
    color: #3b82f6;
    text-decoration: none;
}

.breadcrumb .current {
    color: #1f2937;
}

.main-content {
    padding: 40px 0;
}

.hero-section {
    text-align: center;
    padding: 60px 20px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: #fff;
    border-radius: 12px;
    margin-bottom: 40px;
}

.hero-section h1 {
    font-size: 36px;
    margin-bottom: 15px;
}

.hero-desc {
    font-size: 16px;
    margin-bottom: 30px;
    opacity: 0.95;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 60px;
    margin-top: 30px;
}

.stat-item {
    text-align: center;
}

.stat-number {
    font-size: 32px;
    font-weight: 700;
    display: block;
}

.stat-label {
    font-size: 14px;
    opacity: 0.9;
    margin-top: 5px;
}

.content-section {
    margin-bottom: 50px;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
}

.section-title {
    font-size: 24px;
    color: #1f2937;
}

.section-link {
    color: #3b82f6;
    text-decoration: none;
    font-size: 14px;
}

.quick-nav-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
}

.nav-card {
    background: #fff;
    padding: 30px;
    border-radius: 8px;
    text-decoration: none;
    color: #1f2937;
    border: 1px solid #e5e7eb;
    transition: all 0.3s;
    position: relative;
}

.nav-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
    border-color: #3b82f6;
}

.card-icon {
    font-size: 40px;
    margin-bottom: 15px;
}

.nav-card h3 {
    font-size: 20px;
    margin-bottom: 10px;
    color: #1f2937;
}

.nav-card p {
    font-size: 14px;
    color: #6b7280;
    line-height: 1.6;
}

.card-arrow {
    position: absolute;
    right: 20px;
    bottom: 20px;
    font-size: 20px;
    color: #3b82f6;
}

.article-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.article-card {
    background: #fff;
    padding: 25px;
    border-radius: 8px;
    border: 1px solid #e5e7eb;
    position: relative;
}

.article-card.featured {
    border-color: #3b82f6;
    background: linear-gradient(to right, #fff 0%, #eff6ff 100%);
}

.badge {
    display: inline-block;
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 600;
    margin-bottom: 10px;
}

.badge-hot {
    background: #fee2e2;
    color: #dc2626;
}

.article-card h3 {
    font-size: 18px;
    margin-bottom: 10px;
}

.article-card h3 a {
    color: #1f2937;
    text-decoration: none;
    transition: color 0.3s;
}

.article-card h3 a:hover {
    color: #3b82f6;
}

.article-meta {
    display: flex;
    gap: 15px;
    font-size: 13px;
    color: #6b7280;
    margin-bottom: 10px;
}

.article-excerpt {
    font-size: 14px;
    color: #4b5563;
    line-height: 1.6;
}

.tutorial-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.tutorial-card {
    background: #fff;
    padding: 25px;
    border-radius: 8px;
    text-align: center;
    border: 1px solid #e5e7eb;
    text-decoration: none;
    color: #1f2937;
    transition: all 0.3s;
}

.tutorial-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.tutorial-icon {
    font-size: 36px;
    margin-bottom: 15px;
}

.tutorial-card h4 {
    font-size: 16px;
    margin-bottom: 8px;
    color: #1f2937;
}

.tutorial-card p {
    font-size: 13px;
    color: #6b7280;
}

.highlight-section {
    background: #fff;
    padding: 40px;
    border-radius: 12px;
    margin-bottom: 40px;
}

.china-ai-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 20px;
}

.china-ai-card {
    background: #f9fafb;
    padding: 25px;
    border-radius: 8px;
    border: 1px solid #e5e7eb;
}

.china-ai-card h4 {
    font-size: 18px;
    margin-bottom: 10px;
    color: #1f2937;
}

.china-ai-card p {
    font-size: 14px;
    color: #6b7280;
    margin-bottom: 15px;
    line-height: 1.6;
}

.china-ai-card a {
    color: #3b82f6;
    text-decoration: none;
    font-size: 14px;
    font-weight: 500;
}

.update-timeline {
    background: #fff;
    padding: 30px;
    border-radius: 8px;
}

.update-item {
    display: flex;
    gap: 20px;
    padding: 15px 0;
    border-bottom: 1px solid #e5e7eb;
}

.update-item:last-child {
    border-bottom: none;
}

.update-date {
    font-size: 14px;
    color: #6b7280;
    min-width: 100px;
}

.update-content {
    font-size: 14px;
    color: #4b5563;
    line-height: 1.6;
}

.update-list {
    background: #fff;
    padding: 30px;
    border-radius: 8px;
}

.site-footer {
    background: #1f2937;
    color: #d1d5db;
    padding: 50px 0 20px;
    margin-top: 60px;
}

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

.footer-section h3 {
    color: #fff;
    font-size: 16px;
    margin-bottom: 15px;
}

.footer-section p {
    font-size: 14px;
    line-height: 1.6;
    margin-bottom: 10px;
}

.footer-section a {
    color: #60a5fa;
    text-decoration: none;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 8px;
}

.footer-links a {
    color: #d1d5db;
    text-decoration: none;
    font-size: 14px;
    transition: color 0.3s;
}

.footer-links a:hover {
    color: #60a5fa;
}

.footer-bottom {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid #374151;
    font-size: 13px;
}

.footer-bottom p {
    margin: 5px 0;
}

@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 15px;
    }
    
    .main-nav {
        gap: 15px;
        font-size: 14px;
    }
    
    .hero-section h1 {
        font-size: 28px;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: 20px;
    }
    
    .quick-nav-grid,
    .tutorial-grid,
    .china-ai-grid {
        grid-template-columns: 1fr;
    }
}