/* CSS变量定义 */
:root {
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --accent-color: #f093fb;
    --text-primary: #2d3748;
    --text-secondary: #4a5568;
    --text-muted: #718096;
    --bg-white: #ffffff;
    --bg-light: #f7fafc;
    --bg-card: #ffffff;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.1);
    --border-radius: 12px;
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--bg-light);
}

/* 导航栏 */
.main-header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    box-shadow: var(--shadow-md);
    position: sticky;
    top: 0;
    z-index: 100;
}

.navbar {
    padding: 1rem 0;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: white;
    text-decoration: none;
    transition: var(--transition);
}

.nav-logo:hover {
    transform: scale(1.05);
}

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

.nav-menu a {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    padding: 0.5rem 1rem;
    border-radius: 6px;
}

.nav-menu a:hover,
.nav-menu a.active {
    background: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

/* 主容器 */
.articles-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

/* 英雄区域 */
.hero-section {
    text-align: center;
    padding: 4rem 0;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1), rgba(118, 75, 162, 0.1));
    border-radius: var(--border-radius);
    margin-bottom: 3rem;
}

.hero-section h1 {
    font-size: 3rem;
    font-weight: 300;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.hero-subtitle {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-quote {
    font-size: 1.1rem;
    font-style: italic;
    color: var(--text-muted);
    max-width: 500px;
    margin: 0 auto;
    padding: 1.5rem;
    border-left: 4px solid var(--primary-color);
    background: rgba(255, 255, 255, 0.7);
    border-radius: 0 var(--border-radius) var(--border-radius) 0;
}

.hero-quote cite {
    display: block;
    margin-top: 1rem;
    font-weight: 600;
    color: var(--text-secondary);
}

/* 文章网格 */
.articles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin-bottom: 4rem;
}

/* 文章卡片 */
.article-card {
    background: var(--bg-card);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

.article-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.article-card.featured {
    grid-column: 1 / -1;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0;
}

.article-image {
    position: relative;
    overflow: hidden;
}

.article-image img {
    width: 100%;
    height: 250px;
    object-fit: cover;
    transition: var(--transition);
}

.article-card:hover .article-image img {
    transform: scale(1.05);
}

.article-card.featured .article-image img {
    height: 100%;
    min-height: 400px;
}

.article-content {
    padding: 1.5rem;
}

.article-content h2 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
    line-height: 1.3;
}

.article-card.featured .article-content h2 {
    font-size: 2rem;
}

.article-excerpt {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    line-height: 1.6;
}

.article-quote {
    margin: 1.5rem 0;
    padding: 1rem;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1), rgba(118, 75, 162, 0.1));
    border-left: 4px solid var(--primary-color);
    border-radius: 0 8px 8px 0;
}

.article-quote blockquote {
    font-style: italic;
    color: var(--text-secondary);
    font-size: 1.1rem;
}

.practice-tips,
.tips-list {
    margin: 1.5rem 0;
    padding: 1rem;
    background: var(--bg-light);
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.practice-tips h3,
.tips-list h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.practice-tips ol,
.tips-list ul {
    margin-left: 1rem;
}

.practice-tips li,
.tips-list li {
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

.article-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 1.5rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.read-time {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.read-more {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    padding: 0.5rem 1rem;
    border-radius: 6px;
    border: 2px solid var(--primary-color);
}

.read-more:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-2px);
}

/* 练习基础部分 */
.practice-basics {
    background: var(--bg-card);
    padding: 3rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    margin-bottom: 3rem;
    text-align: center;
}

.practice-basics h2 {
    font-size: 2.5rem;
    font-weight: 300;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.section-subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

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

.basic-tip {
    text-align: center;
    padding: 1.5rem;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.05), rgba(118, 75, 162, 0.05));
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.basic-tip:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.tip-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.basic-tip h3 {
    font-size: 1.3rem;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.basic-tip p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* CTA部分 */
.cta-section {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    text-align: center;
    padding: 4rem 2rem;
    border-radius: var(--border-radius);
    margin-bottom: 3rem;
}

.cta-content h2 {
    font-size: 2.5rem;
    font-weight: 300;
    margin-bottom: 1rem;
}

.cta-content p {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

.cta-button {
    display: inline-block;
    background: white;
    color: var(--primary-color);
    padding: 1rem 2rem;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 600;
    font-size: 1.1rem;
    transition: var(--transition);
    box-shadow: var(--shadow-lg);
}

.cta-button:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-xl);
}

/* 页脚 */
.main-footer {
    background: var(--text-primary);
    color: white;
    padding: 2rem 0;
    text-align: center;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.footer-links {
    display: flex;
    gap: 2rem;
}

.footer-links a {
    color: white;
    text-decoration: none;
    transition: var(--transition);
}

.footer-links a:hover {
    color: var(--accent-color);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .nav-container {
        padding: 0 1rem;
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-menu {
        gap: 1rem;
    }
    
    .articles-container {
        padding: 1rem;
    }
    
    .hero-section {
        padding: 2rem 1rem;
    }
    
    .hero-section h1 {
        font-size: 2rem;
    }
    
    .articles-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .article-card.featured {
        grid-template-columns: 1fr;
    }
    
    .article-card.featured .article-image img {
        height: 250px;
        min-height: auto;
    }
    
    .practice-basics {
        padding: 2rem 1rem;
    }
    
    .practice-basics h2 {
        font-size: 2rem;
    }
    
    .basics-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .cta-section {
        padding: 3rem 1rem;
    }
    
    .cta-content h2 {
        font-size: 2rem;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
    }
    
    .footer-links {
        gap: 1rem;
    }
}

@media (max-width: 480px) {
    .hero-section h1 {
        font-size: 1.8rem;
    }
    
    .article-content {
        padding: 1rem;
    }
    
    .article-meta {
        flex-direction: column;
        gap: 1rem;
        align-items: flex-start;
    }
    
    .nav-menu {
        flex-direction: column;
        gap: 0.5rem;
    }
}