/* 基础样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    line-height: 1.6;
    color: #333;
    background: #fff;
}

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

/* 导航栏 */
.navbar {
    background: #fff;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
}

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

.nav-logo h2 {
    color: #4F46E5;
    font-weight: 700;
}

.nav-menu {
    display: flex;
    gap: 2rem;
}

.nav-link {
    text-decoration: none;
    color: #6B7280;
    font-weight: 500;
    transition: color 0.3s;
}

.nav-link:hover,
.nav-link.active {
    color: #4F46E5;
}

/* 英雄区域 */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 160px 0 100px;
    text-align: center;
}

.hero-content h1 {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
}

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

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

/* 按钮样式 */
.btn {
    padding: 12px 30px;
    border: none;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s;
    cursor: pointer;
    display: inline-block;
    text-align: center;
}

.btn-primary {
    background: #4F46E5;
    color: white;
}

.btn-primary:hover {
    background: #4338CA;
    transform: translateY(-2px);
}

.btn-secondary {
    background: transparent;
    color: white;
    border: 2px solid white;
}

.btn-secondary:hover {
    background: white;
    color: #4F46E5;
}

.btn-premium {
    background: linear-gradient(135deg, #F59E0B, #D97706);
    color: white;
    width: 100%;
}

.btn-premium:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(245, 158, 11, 0.3);
}

/* 文章网格 */
.featured-articles {
    padding: 80px 0;
    background: #F9FAFB;
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: #1F2937;
}

.articles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
}

.article-card {
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
    transition: transform 0.3s, box-shadow 0.3s;
    position: relative;
}

.article-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 20px 25px rgba(0,0,0,0.1);
}

.article-badge {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: #10B981;
    color: white;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
}

.article-badge.premium {
    background: #F59E0B;
}

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

.article-content {
    padding: 1.5rem;
}

.article-content h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: #1F2937;
}

.article-content p {
    color: #6B7280;
    margin-bottom: 1rem;
}

.article-meta {
    display: flex;
    justify-content: space-between;
    font-size: 0.875rem;
    color: #9CA3AF;
    margin-bottom: 1rem;
}

.price-tag {
    font-size: 1.5rem;
    font-weight: 700;
    color: #F59E0B;
    margin: 1rem 0;
}

.read-more {
    color: #4F46E5;
    text-decoration: none;
    font-weight: 600;
}

.read-more:hover {
    text-decoration: underline;
}

/* 付费区域 */
.premium-section {
    padding: 80px 0;
}

.premium-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.premium-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
    text-align: center;
    position: relative;
    border: 1px solid #E5E7EB;
    transition: transform 0.3s;
}

.premium-card:hover {
    transform: translateY(-5px);
}

.premium-card.featured {
    border: 2px solid #F59E0B;
    transform: scale(1.05);
}

.premium-badge {
    position: absolute;
    top: -10px;
    left: 50%;
    transform: translateX(-50%);
    background: #F59E0B;
    color: white;
    padding: 5px 15px;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
}

.premium-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, #4F46E5, #7C3AED);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    color: white;
    font-size: 2rem;
}

.premium-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: #1F2937;
}

.premium-card p {
    color: #6B7280;
    margin-bottom: 1.5rem;
}

.premium-price {
    font-size: 2.5rem;
    font-weight: 700;
    color: #1F2937;
    margin-bottom: 1.5rem;
}

.premium-features {
    list-style: none;
    margin-bottom: 2rem;
}

.premium-features li {
    padding: 0.5rem 0;
    color: #6B7280;
}

.premium-features i {
    color: #10B981;
    margin-right: 0.5rem;
}

/* 页脚 */
.footer {
    background: #1F2937;
    color: white;
    padding: 3rem 0;
}

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

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

.footer-section a {
    display: block;
    color: #D1D5DB;
    text-decoration: none;
    margin-bottom: 0.5rem;
    transition: color 0.3s;
}

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

/* 响应式设计 */
@media (max-width: 768px) {
    .hero-content h1 {
        font-size: 2.5rem;
    }
    
    .nav-menu {
        display: none;
    }
    
    .articles-grid,
    .premium-grid {
        grid-template-columns: 1fr;
    }
    
    .premium-card.featured {
        transform: none;
    }
}