/* 重置样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #3178c6;
    --primary-dark: #2964a3;
    --secondary-color: #64748b;
    --accent-color: #06b6d4;
    --success-color: #10b981;
    --text-primary: #1e293b;
    --text-secondary: #475569;
    --text-light: #94a3b8;
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-alt: #f1f5f9;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --font-main: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'Monaco', 'Consolas', 'Courier New', monospace;
    --transition: all 0.3s ease;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-main);
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-secondary);
}

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

/* 头部样式 */
.header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-md);
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
}

.subtitle {
    font-size: 0.875rem;
    opacity: 0.9;
}

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

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

.nav-list a:hover,
.nav-list a.active {
    background: rgba(255, 255, 255, 0.2);
}

/* 主要内容区域 */
main {
    min-height: calc(100vh - 200px);
}

/* 英雄区域 */
.hero {
    padding: 5rem 0;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
}

.hero-content {
    text-align: center;
    margin-bottom: 4rem;
}

.hero-content h2 {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    line-height: 1.2;
}

.hero-content p {
    font-size: 1.25rem;
    opacity: 0.95;
    max-width: 800px;
    margin: 0 auto 2rem;
}

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

.btn {
    display: inline-block;
    padding: 1rem 2rem;
    border-radius: var(--radius-lg);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

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

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

.feature-card {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    padding: 2rem;
    border-radius: var(--radius-lg);
    text-align: center;
    transition: var(--transition);
}

.feature-card:hover {
    transform: translateY(-5px);
    background: rgba(255, 255, 255, 0.15);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.feature-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
}

.feature-card p {
    opacity: 0.9;
}

/* 通用区块样式 */
.section {
    padding: 5rem 0;
}

.section-alt {
    background: var(--bg-alt);
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-header h2 {
    font-size: 2.5rem;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.section-header p {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

/* 主题卡片网格 */
.topic-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.topic-card {
    background: white;
    padding: 2rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

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

.topic-badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background: var(--primary-color);
    color: white;
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.topic-badge.advanced {
    background: var(--accent-color);
}

.topic-card h3 {
    font-size: 1.5rem;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.topic-card > p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.code-preview {
    background: var(--bg-alt);
    padding: 1rem;
    border-radius: var(--radius-md);
    margin-bottom: 1.5rem;
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--text-primary);
    overflow-x: auto;
    border: 1px solid var(--border-color);
}

.learn-more {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
}

.learn-more:hover {
    color: var(--primary-dark);
}

/* 最佳实践列表 */
.practices-list {
    display: grid;
    gap: 1.5rem;
}

.practice-item {
    background: white;
    padding: 2rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    display: flex;
    gap: 2rem;
    align-items: flex-start;
    transition: var(--transition);
}

.practice-item:hover {
    box-shadow: var(--shadow-xl);
}

.practice-number {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--primary-color);
    line-height: 1;
    min-width: 80px;
    text-align: center;
}

.practice-item h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.practice-item p {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* 学习资源网格 */
.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.resource-card {
    background: white;
    padding: 2rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: var(--transition);
}

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

.resource-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.resource-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.resource-card > p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.resource-link {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
}

.resource-link:hover {
    color: var(--primary-dark);
}

/* 页脚样式 */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 3rem 0 1rem;
}

.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;
}

.footer-section p {
    opacity: 0.8;
    line-height: 1.8;
}

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

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

.footer-links a {
    color: white;
    text-decoration: none;
    opacity: 0.8;
    transition: var(--transition);
}

.footer-links a:hover {
    opacity: 1;
}

.footer-section p a {
    color: white;
    text-decoration: none;
    opacity: 0.8;
    transition: var(--transition);
}

.footer-section p a:hover {
    opacity: 1;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-bottom p {
    opacity: 0.6;
    font-size: 0.875rem;
}

/* 返回顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    box-shadow: var(--shadow-lg);
    z-index: 1000;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background: var(--primary-dark);
    transform: translateY(-3px);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .header .container {
        flex-direction: column;
        text-align: center;
    }

    .nav-list {
        gap: 1rem;
        flex-wrap: wrap;
        justify-content: center;
    }

    .hero-content h2 {
        font-size: 2rem;
    }

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

    .section-header h2 {
        font-size: 2rem;
    }

    .practice-item {
        flex-direction: column;
        text-align: center;
    }

    .practice-number {
        margin: 0 auto;
    }

    .back-to-top {
        bottom: 1rem;
        right: 1rem;
    }
}

@media (max-width: 480px) {
    .hero-content h2 {
        font-size: 1.5rem;
    }

    .hero-buttons {
        flex-direction: column;
        align-items: stretch;
    }

    .btn {
        width: 100%;
    }

    .topic-grid,
    .resources-grid {
        grid-template-columns: 1fr;
    }
}

/* 滚动条样式 */
::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--primary-color);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--primary-dark);
}

/* 选中文本样式 */
::selection {
    background: var(--primary-color);
    color: white;
}

/* 链接动画 */
a {
    transition: var(--transition);
}

/* 按钮点击效果 */
.btn:active {
    transform: scale(0.98);
}