/* OpenCode 深度教程 - 主样式文件 */
/* 基于 Claude Code 教程网站风格设计 */

/* ===== 性能优化 ===== */

/* 字体渲染优化 */
html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

/* 图片懒加载占位样式 */
img[loading="lazy"] {
  background: linear-gradient(90deg, var(--bg-secondary) 25%, var(--bg-tertiary) 50%, var(--bg-secondary) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
}

img[loading="lazy"][src] {
  animation: none;
  background: none;
}

@keyframes shimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

/* will-change 性能提示 */
.sidebar {
  will-change: transform;
}

.back-to-top {
  will-change: opacity, visibility, transform;
}

.feature-card,
.article-nav-item,
.btn {
  will-change: transform;
}

/* 减少重绘的过渡效果 */
.theme-toggle,
.search-input,
.navbar-nav a {
  will-change: background-color, border-color, color;
}

/* ===== 主题变量 ===== */

:root {
  /* 主题色 */
  --primary-color: #10b981;
  --primary-hover: #059669;
  --primary-light: rgba(16, 185, 129, 0.1);

  /* 背景色 */
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;

  /* 文字色 */
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  /* 边框色 */
  --border-color: #334155;
  --border-light: #475569;

  /* 代码块 */
  --code-bg: #1e293b;
  --code-text: #e2e8f0;

  /* 字体 */
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, 'SF Mono', Menlo, Consolas, 'Liberation Mono', monospace;
}

/* 亮色模式 */
.light-mode {
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #e2e8f0;
  --text-primary: #1e293b;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --border-color: #e2e8f0;
  --border-light: #cbd5e1;
  --code-bg: #f1f5f9;
  --code-text: #1e293b;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  min-height: 100vh;
}

/* 滚动条样式 */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

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

::-webkit-scrollbar-thumb {
  background: var(--border-light);
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* 链接样式 */
a {
  color: var(--primary-color);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--primary-hover);
  text-decoration: underline;
}

/* 顶部导航 */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 60px;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  backdrop-filter: blur(8px);
}

.navbar-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
}

.navbar-brand:hover {
  text-decoration: none;
  color: var(--primary-color);
}

.navbar-brand .logo {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, var(--primary-color), #06b6d4);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  color: white;
  font-size: 16px;
}

.navbar-nav {
  display: flex;
  align-items: center;
  gap: 20px;
}

.navbar-nav a {
  color: var(--text-secondary);
  font-size: 0.9rem;
  padding: 8px 12px;
  border-radius: 6px;
  transition: all 0.2s ease;
}

.navbar-nav a:hover {
  color: var(--text-primary);
  background: var(--bg-tertiary);
  text-decoration: none;
}

.navbar-right {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* 搜索框 */
.search-box {
  position: relative;
}

.search-input {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 8px 16px 8px 40px;
  color: var(--text-primary);
  font-size: 0.9rem;
  width: 240px;
  transition: all 0.2s ease;
}

.search-input:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.search-input::placeholder {
  color: var(--text-muted);
}

.search-icon {
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  pointer-events: none;
}

/* 主题切换按钮 */
.theme-toggle {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 8px;
  cursor: pointer;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s ease;
}

.theme-toggle:hover {
  color: var(--text-primary);
  border-color: var(--border-light);
}

/* 侧边栏 */
.sidebar {
  position: fixed;
  top: 60px;
  left: 0;
  bottom: 0;
  width: 280px;
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  overflow-y: auto;
  padding: 20px 0;
  z-index: 900;
  transition: transform 0.3s ease;
}

.sidebar-section {
  margin-bottom: 24px;
}

.sidebar-title {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  padding: 8px 24px;
  margin-bottom: 4px;
}

.sidebar-nav {
  list-style: none;
}

.sidebar-nav li {
  margin: 2px 0;
}

.sidebar-nav a {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 24px;
  color: var(--text-secondary);
  font-size: 0.9rem;
  transition: all 0.2s ease;
  border-left: 3px solid transparent;
}

.sidebar-nav a:hover {
  color: var(--text-primary);
  background: var(--bg-tertiary);
  text-decoration: none;
}

.sidebar-nav a.active {
  color: var(--primary-color);
  background: var(--primary-light);
  border-left-color: var(--primary-color);
}

.sidebar-nav .chapter-number {
  font-size: 0.8rem;
  color: var(--text-muted);
  min-width: 28px;
}

/* 主内容区 */
.main-content {
  margin-left: 280px;
  margin-top: 60px;
  min-height: calc(100vh - 60px);
  padding: 40px 60px;
  max-width: 900px;
}

/* 面包屑导航 */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 24px;
}

.breadcrumb a {
  color: var(--text-muted);
}

.breadcrumb a:hover {
  color: var(--primary-color);
}

.breadcrumb-separator {
  color: var(--text-muted);
}

/* 文章标题 */
.article-header {
  margin-bottom: 40px;
}

.article-title {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 16px;
  line-height: 1.2;
}

.article-meta {
  display: flex;
  align-items: center;
  gap: 16px;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.article-meta .tag {
  background: var(--primary-light);
  color: var(--primary-color);
  padding: 4px 12px;
  border-radius: 20px;
  font-size: 0.8rem;
}

/* 文章内容 */
.article-content {
  color: var(--text-secondary);
  font-size: 1rem;
  line-height: 1.8;
}

.article-content h2 {
  font-size: 1.75rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 48px 0 20px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
}

.article-content h3 {
  font-size: 1.375rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 36px 0 16px;
}

.article-content h4 {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 28px 0 12px;
}

.article-content p {
  margin-bottom: 16px;
}

.article-content ul,
.article-content ol {
  margin: 16px 0;
  padding-left: 24px;
}

.article-content li {
  margin: 8px 0;
}

.article-content strong {
  color: var(--text-primary);
  font-weight: 600;
}

/* 代码样式 */
.article-content code {
  font-family: var(--font-mono);
  background: var(--code-bg);
  color: #f472b6;
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.875em;
}

.article-content pre {
  background: var(--code-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 20px;
  overflow-x: auto;
  margin: 20px 0;
  position: relative;
}

.article-content pre code {
  background: none;
  padding: 0;
  color: var(--code-text);
  font-size: 0.9rem;
  line-height: 1.6;
}

/* 代码块语言标签 */
.code-block {
  position: relative;
}

.code-lang {
  position: absolute;
  top: 8px;
  right: 12px;
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
}

.copy-btn {
  position: absolute;
  top: 8px;
  right: 60px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 4px;
  padding: 4px 8px;
  font-size: 0.75rem;
  color: var(--text-muted);
  cursor: pointer;
  opacity: 0;
  transition: all 0.2s ease;
}

.code-block:hover .copy-btn {
  opacity: 1;
}

.copy-btn:hover {
  color: var(--text-primary);
  border-color: var(--border-light);
}

/* 提示框 */
.tip-box {
  background: var(--bg-secondary);
  border-left: 4px solid var(--primary-color);
  border-radius: 0 8px 8px 0;
  padding: 16px 20px;
  margin: 20px 0;
}

.tip-box.warning {
  border-left-color: #f59e0b;
  background: rgba(245, 158, 11, 0.1);
}

.tip-box.danger {
  border-left-color: #ef4444;
  background: rgba(239, 68, 68, 0.1);
}

.tip-box.info {
  border-left-color: #3b82f6;
  background: rgba(59, 130, 246, 0.1);
}

.tip-box-title {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.tip-box-content {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

/* 表格样式 */
.article-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0;
  font-size: 0.9rem;
}

.article-content th,
.article-content td {
  padding: 12px 16px;
  text-align: left;
  border: 1px solid var(--border-color);
}

.article-content th {
  background: var(--bg-secondary);
  color: var(--text-primary);
  font-weight: 600;
}

.article-content tr:nth-child(even) {
  background: var(--bg-secondary);
}

/* 图片样式 */
.article-content img {
  max-width: 100%;
  border-radius: 8px;
  margin: 20px 0;
  border: 1px solid var(--border-color);
}

/* 引用样式 */
.article-content blockquote {
  border-left: 4px solid var(--primary-color);
  padding-left: 20px;
  margin: 20px 0;
  color: var(--text-muted);
  font-style: italic;
}

/* 上一篇/下一篇导航 */
.article-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 60px;
  padding-top: 24px;
  border-top: 1px solid var(--border-color);
  gap: 20px;
}

.article-nav-item {
  flex: 1;
  padding: 20px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  transition: all 0.2s ease;
}

.article-nav-item:hover {
  border-color: var(--primary-color);
  text-decoration: none;
}

.article-nav-item.prev {
  text-align: left;
}

.article-nav-item.next {
  text-align: right;
}

.article-nav-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.article-nav-title {
  font-weight: 600;
  color: var(--text-primary);
}

/* 目录导航 (右侧) */
.toc {
  position: fixed;
  top: 100px;
  right: 40px;
  width: 220px;
  max-height: calc(100vh - 140px);
  overflow-y: auto;
  font-size: 0.85rem;
}

.toc-title {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-bottom: 12px;
}

.toc-list {
  list-style: none;
  border-left: 1px solid var(--border-color);
}

.toc-list li {
  margin: 4px 0;
}

.toc-list a {
  display: block;
  padding: 4px 16px;
  color: var(--text-muted);
  border-left: 2px solid transparent;
  margin-left: -1px;
  transition: all 0.2s ease;
}

.toc-list a:hover {
  color: var(--text-primary);
  text-decoration: none;
}

.toc-list a.active {
  color: var(--primary-color);
  border-left-color: var(--primary-color);
}

/* 首页样式 */
.hero {
  text-align: center;
  padding: 80px 20px;
  max-width: 800px;
  margin: 0 auto;
}

.hero-title {
  font-size: 3.5rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 20px;
  background: linear-gradient(135deg, var(--primary-color), #06b6d4);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.5rem;
  color: var(--text-secondary);
  margin-bottom: 32px;
}

.hero-description {
  font-size: 1.1rem;
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto 40px;
  line-height: 1.8;
}

.hero-buttons {
  display: flex;
  gap: 16px;
  justify-content: center;
}

/* 新版Hero样式 */
.hero.hero-new {
  text-align: left !important;
  padding: 100px 20px 80px !important;
  max-width: 900px !important;
  margin: 0 auto !important;
}

.hero-badge {
  display: inline-flex !important;
  align-items: center !important;
  gap: 8px !important;
  padding: 8px 16px !important;
  background: rgba(16, 185, 129, 0.1) !important;
  border: 1px solid rgba(16, 185, 129, 0.3) !important;
  border-radius: 20px !important;
  font-size: 0.9rem !important;
  color: var(--primary-color) !important;
  margin-bottom: 32px !important;
}

.badge-dot {
  width: 8px;
  height: 8px;
  background: var(--primary-color);
  border-radius: 50%;
  display: inline-block;
}

.hero-title-new {
  margin-bottom: 32px !important;
}

.hero-title-new .title-highlight {
  display: block !important;
  font-size: 4.5rem !important;
  font-weight: 800 !important;
  font-style: italic !important;
  background: linear-gradient(135deg, #3b82f6, #06b6d4) !important;
  -webkit-background-clip: text !important;
  -webkit-text-fill-color: transparent !important;
  background-clip: text !important;
  margin-bottom: 8px !important;
  line-height: 1.1 !important;
}

.hero-title-new .title-dark {
  display: block !important;
  font-size: 3.5rem !important;
  font-weight: 800 !important;
  color: var(--text-primary) !important;
  -webkit-text-fill-color: var(--text-primary) !important;
  background: none !important;
  line-height: 1.2 !important;
}

.hero-description-new {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 700px;
  line-height: 1.9;
  margin-bottom: 40px;
}

.hero-buttons-new {
  display: flex;
  gap: 16px;
  margin-bottom: 48px;
  flex-wrap: wrap;
}

.btn-primary-new {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 28px;
  background: var(--primary-color);
  color: white;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 600;
  transition: all 0.2s ease;
}

.btn-primary-new:hover {
  background: var(--primary-hover);
  text-decoration: none;
  color: white;
  transform: translateY(-2px);
}

.btn-outline-new {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 28px;
  background: var(--bg-secondary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 600;
  transition: all 0.2s ease;
}

.btn-outline-new:hover {
  background: var(--bg-tertiary);
  text-decoration: none;
  color: var(--text-primary);
  transform: translateY(-2px);
}

.hero-stats {
  display: flex;
  align-items: center;
  gap: 16px;
}

.stats-avatars {
  display: flex;
}

.stats-avatars .avatar {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: linear-gradient(135deg, #64748b, #475569);
  border: 2px solid var(--bg-primary);
  margin-left: -10px;
}

.stats-avatars .avatar:first-child {
  margin-left: 0;
}

.stats-info {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.95rem;
}

.stats-rating {
  color: #fbbf24;
  font-weight: 600;
}

.stats-text {
  color: var(--text-secondary);
}

@media (max-width: 768px) {
  .hero-new {
    text-align: center;
    padding: 60px 20px;
  }

  .hero-badge {
    margin-bottom: 24px;
  }

  .hero-title-new .title-highlight {
    font-size: 2.5rem;
  }

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

  .hero-buttons-new {
    justify-content: center;
  }

  .hero-stats {
    justify-content: center;
    flex-wrap: wrap;
  }
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  transition: all 0.2s ease;
  cursor: pointer;
  border: none;
}

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

.btn-primary:hover {
  background: var(--primary-hover);
  text-decoration: none;
  color: white;
}

.btn-secondary {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
}

.btn-secondary:hover {
  background: var(--border-color);
  text-decoration: none;
}

/* 特性卡片 */
.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
  max-width: 1200px;
  margin: 0 auto;
  padding: 40px 20px;
}

.feature-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 24px;
  transition: all 0.2s ease;
}

.feature-card:hover {
  border-color: var(--primary-color);
  transform: translateY(-2px);
}

.feature-icon {
  width: 48px;
  height: 48px;
  background: var(--primary-light);
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
  color: var(--primary-color);
  font-size: 24px;
}

.feature-title {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.feature-description {
  color: var(--text-muted);
  font-size: 0.9rem;
  line-height: 1.6;
}

/* 章节列表 */
.chapter-list {
  max-width: 800px;
  margin: 40px auto;
  padding: 0 20px;
}

.chapter-group {
  margin-bottom: 32px;
}

.chapter-group-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-color);
}

.chapter-items {
  list-style: none;
}

.chapter-item {
  margin: 8px 0;
}

.chapter-item a {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  color: var(--text-secondary);
  transition: all 0.2s ease;
}

.chapter-item a:hover {
  border-color: var(--primary-color);
  color: var(--text-primary);
  text-decoration: none;
}

.chapter-item .num {
  font-size: 0.85rem;
  color: var(--text-muted);
  min-width: 40px;
}

/* 页脚 */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 40px 20px;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-bottom: 16px;
}

.footer-links a {
  color: var(--text-muted);
}

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

/* 移动端菜单按钮 */
.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  padding: 8px;
  cursor: pointer;
  color: var(--text-secondary);
}

/* 响应式设计 */
@media (max-width: 1400px) {
  .toc {
    display: none;
  }
}

@media (max-width: 1024px) {
  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.active {
    transform: translateX(0);
  }

  .main-content {
    margin-left: 0;
    padding: 30px 20px;
  }

  .mobile-menu-btn {
    display: block;
  }
}

@media (max-width: 768px) {
  .navbar-nav {
    display: none;
  }

  .search-input {
    width: 180px;
  }

  .hero-title {
    font-size: 2.5rem;
  }

  .hero-subtitle {
    font-size: 1.25rem;
  }

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

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

  .article-nav {
    flex-direction: column;
  }
}

/* 代码高亮 */
.hljs-keyword {
  color: #c792ea;
}

.hljs-string {
  color: #c3e88d;
}

.hljs-number {
  color: #f78c6c;
}

.hljs-comment {
  color: #546e7a;
  font-style: italic;
}

.hljs-function {
  color: #82aaff;
}

.hljs-built_in {
  color: #ffcb6b;
}

.hljs-attr {
  color: #ffcb6b;
}

.hljs-variable {
  color: #f07178;
}

/* 搜索结果 */
.search-results {
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  margin-top: 4px;
  max-height: 400px;
  overflow-y: auto;
  display: none;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

.search-results.active {
  display: block;
}

.search-result-item {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border-color);
  cursor: pointer;
  transition: background 0.2s ease;
}

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

.search-result-item:hover {
  background: var(--bg-tertiary);
}

.search-result-title {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.search-result-excerpt {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* 加载动画 */
.loading {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 40px;
}

.loading-spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--border-color);
  border-top-color: var(--primary-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* 回到顶部按钮 */
.back-to-top {
  position: fixed;
  bottom: 40px;
  right: 40px;
  width: 48px;
  height: 48px;
  background: var(--primary-color);
  color: white;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  box-shadow: 0 4px 12px rgba(16, 185, 129, 0.3);
}

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

.back-to-top:hover {
  background: var(--primary-hover);
  transform: translateY(-2px);
}

/* 打印样式 */
@media print {
  .navbar,
  .sidebar,
  .toc,
  .back-to-top,
  .article-nav {
    display: none !important;
  }

  .main-content {
    margin: 0;
    padding: 20px;
    max-width: none;
  }

  body {
    background: white;
    color: black;
  }
}