/* ==================== 全局样式 - 清新风格 ==================== */
:root {
  --primary-color: #4ECDC4;
  --primary-light: #7EDCD6;
  --primary-dark: #3BB3AB;
  --accent-color: #FF6B9D;
  --bg-color: #FDFDFD;
  --card-bg: #FFFFFF;
  --text-primary: #2C3E50;
  --text-secondary: #7F8C8D;
  --border-color: #E8F5E9;
  --shadow: 0 4px 20px rgba(78, 205, 196, 0.15);
  --shadow-hover: 0 8px 30px rgba(78, 205, 196, 0.25);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  background: linear-gradient(135deg, #FDFDFD 0%, #F5F9FA 100%);
  color: var(--text-primary);
  line-height: 1.8;
  padding-top: 70px;
  font-size: 16px;
}

/* ==================== 顶部导航栏 - 现代化设计 ==================== */
.top-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 70px;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(20px);
  box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 40px;
  z-index: 1001;
  border-bottom: 1px solid rgba(78, 205, 196, 0.2);
}

.logo {
  font-size: 26px;
  font-weight: 700;
  background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: 1px;
  text-decoration: none;
  cursor: pointer;
  transition: transform 0.3s ease;
}

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

.nav-menu {
  display: flex;
  gap: 8px;
  background: linear-gradient(135deg, rgba(78, 205, 196, 0.1), rgba(255, 107, 157, 0.1));
  padding: 8px 16px;
  border-radius: 30px;
}

.nav-item {
  padding: 12px 24px;
  border-radius: 20px;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  color: var(--text-secondary);
  font-weight: 500;
  font-size: 15px;
  position: relative;
  z-index: 1;
}

.nav-item::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
  opacity: 0;
  transition: opacity 0.3s ease;
  border-radius: 20px;
  z-index: -1;
}

.nav-item:hover::before,
.nav-item.active::before {
  opacity: 0.85;
}

.nav-item:hover,
.nav-item.active {
  color: #ffffff !important;
  font-weight: 600;
  transform: translateY(-2px);
}

/* ==================== 主容器 ==================== */
.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 30px 40px;
  min-height: calc(100vh - 70px);
}

/* ==================== 卡片通用样式 ==================== */
.card {
  background: var(--card-bg);
  border-radius: 20px;
  box-shadow: var(--shadow);
  padding: 30px;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  border: 1px solid var(--border-color);
}

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

/* ==================== 内容标题 ==================== */
.content-header {
  margin-bottom: 30px;
}

.content-title {
  font-size: 32px;
  font-weight: 700;
  background: linear-gradient(135deg, var(--text-primary), var(--primary-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 12px;
}

.content-subtitle {
  color: var(--text-secondary);
  font-size: 16px;
}

/* ==================== 占位提示 ==================== */
.placeholder-message {
  text-align: center;
  padding: 80px 20px;
  color: var(--text-secondary);
  font-size: 18px;
}

.placeholder-message p {
  margin: 0;
}

/* ==================== 网页推荐卡片 ==================== */
.recommendations-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 24px;
}

.recommendation-card {
  background: var(--card-bg);
  border-radius: 16px;
  padding: 28px;
  box-shadow: var(--shadow);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  border: 1px solid var(--border-color);
  position: relative;
  overflow: hidden;
}

.recommendation-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
  opacity: 0;
  transition: opacity 0.3s ease;
}

.recommendation-card:hover::before {
  opacity: 1;
}

.recommendation-card:hover {
  box-shadow: var(--shadow-hover);
  transform: translateY(-8px);
}

.card-title {
  font-size: 20px;
  color: var(--text-primary);
  margin-bottom: 12px;
  font-weight: 600;
}

.card-description {
  color: var(--text-secondary);
  font-size: 15px;
  margin-bottom: 20px;
  line-height: 1.6;
}

.card-link {
  display: inline-block;
  padding: 10px 24px;
  background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
  color: white;
  text-decoration: none;
  border-radius: 25px;
  font-size: 14px;
  font-weight: 500;
  transition: all 0.3s ease;
}

.card-link:hover {
  background: linear-gradient(135deg, var(--primary-dark), var(--primary-color));
  transform: scale(1.05);
  box-shadow: 0 4px 15px rgba(78, 205, 196, 0.4);
}

.card-category {
  display: inline-block;
  padding: 6px 14px;
  background: linear-gradient(135deg, rgba(78, 205, 196, 0.15), rgba(78, 205, 196, 0.1));
  color: var(--primary-dark);
  border-radius: 12px;
  font-size: 13px;
  font-weight: 500;
  margin-top: 15px;
  border: 1px solid rgba(78, 205, 196, 0.3);
}

/* ==================== Markdown 渲染样式 ==================== */
.markdown-body {
  background: var(--card-bg);
  padding: 40px;
  border-radius: 20px;
  box-shadow: var(--shadow);
  border: 1px solid var(--border-color);
  line-height: 1.9;
}

.markdown-body h1 {
  font-size: 36px;
  color: var(--text-primary);
  margin-bottom: 24px;
  padding-bottom: 16px;
  border-bottom: 3px solid var(--primary-light);
}

.markdown-body h2 {
  font-size: 30px;
  color: var(--text-primary);
  margin-top: 40px;
  margin-bottom: 20px;
  padding-bottom: 12px;
  border-bottom: 1px solid rgba(78, 205, 196, 0.25);
}

.markdown-body h3 {
  font-size: 24px;
  color: var(--text-primary);
  margin-top: 32px;
  margin-bottom: 16px;
}

.markdown-body p {
  margin-bottom: 18px;
  color: var(--text-primary);
}

.markdown-body a {
  color: var(--primary-color);
  text-decoration: none;
  transition: color 0.3s ease;
  border-bottom: 1px dashed var(--primary-color);
}

.markdown-body a:hover {
  color: var(--accent-color);
  border-bottom-style: solid;
}

.markdown-body ul,
.markdown-body ol {
  margin-bottom: 20px;
  padding-left: 30px;
}

.markdown-body li {
  margin-bottom: 10px;
  color: var(--text-primary);
}

.markdown-body code {
  background: linear-gradient(135deg, rgba(255, 107, 157, 0.15), rgba(255, 107, 157, 0.08));
  color: #E91E63;
  padding: 3px 8px;
  border-radius: 6px;
  font-family: 'Consolas', 'Monaco', 'Courier New', monospace;
  font-size: 14px;
  font-weight: 500;
  border: 1px solid rgba(255, 107, 157, 0.3);
}

.markdown-body pre {
  background: #F8F9FA;
  border-radius: 16px;
  overflow: hidden;
  margin-bottom: 24px;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
  border: 1px solid var(--border-color);
}

.markdown-body pre code {
  background: transparent;
  color: inherit;
  padding: 0;
  border: none;
  font-size: 14px;
  font-weight: 400;
  display: block;
  overflow-x: auto;
}

.markdown-body blockquote {
  border-left: 4px solid var(--primary-color);
  padding: 16px 20px;
  margin: 20px 0;
  color: var(--text-secondary);
  font-style: italic;
  background: linear-gradient(135deg, rgba(78, 205, 196, 0.1), rgba(78, 205, 196, 0.05));
  border-radius: 0 12px 12px 0;
}

.markdown-body table {
  width: 100%;
  max-width: 800px;
  margin: 24px auto;
  border-collapse: separate;
  border-spacing: 0;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
  border: 1px solid var(--border-color);
}

.markdown-body thead {
  background: linear-gradient(135deg, rgba(126, 220, 214, 0.15), rgba(126, 220, 214, 0.05));
}

.markdown-body th,
.markdown-body td {
  padding: 14px 18px;
  text-align: left;
  border-bottom: 1px solid var(--border-color);
  border-right: 1px solid var(--border-color);
}

.markdown-body th:last-child,
.markdown-body td:last-child {
  border-right: none;
}

.markdown-body th {
  color: var(--primary-dark);
  font-weight: 600;
  font-size: 15px;
}

.markdown-body th:first-child {
  border-top-left-radius: 0;
}

.markdown-body th:last-child {
  border-top-right-radius: 0;
}

.markdown-body tr:last-child td {
  border-bottom: none;
}

.markdown-body tr:hover td {
  background: rgba(78, 205, 196, 0.05);
}

/* 代码块标签样式 */
.markdown-body pre code::before {
  display: none;
}

/* 数学公式样式 */
.katex-display {
  margin: 20px 0;
  overflow-x: auto;
  padding: 16px;
  background: rgba(78, 205, 196, 0.05);
  border-radius: 12px;
}

.katex {
  font-size: 1.1em;
}

/* 脚注样式 */
.markdown-body .footnote-ref {
  font-size: 0.8em;
  vertical-align: super;
  color: var(--primary-color);
  cursor: pointer;
}

.markdown-body .footnote {
  font-size: 0.9em;
  color: var(--text-secondary);
  border-top: 2px solid var(--border-color);
  padding-top: 16px;
  margin-top: 32px;
}

/* 分隔线 */
.markdown-body hr {
  border: none;
  border-top: 1px solid #e1e4e8;
  margin: 32px 0;
}

/* ==================== 响应式设计 ==================== */
@media (max-width: 768px) {
  body {
    padding-top: 64px;
  }

  .top-nav {
    height: 64px;
    padding: 0 16px;
  }

  .logo {
    font-size: 22px;
  }

  .nav-menu {
    gap: 4px;
    padding: 6px 12px;
  }

  .nav-item {
    padding: 10px 16px;
    font-size: 14px;
  }

  .container {
    padding: 20px 16px;
  }

  .content-title {
    font-size: 24px;
  }

  .recommendations-grid {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .markdown-body {
    padding: 24px;
  }

  .markdown-body h1 {
    font-size: 28px;
  }

  .markdown-body h2 {
    font-size: 24px;
  }
}

@media (max-width: 480px) {
  .nav-item {
    padding: 8px 12px;
    font-size: 13px;
  }

  .card {
    padding: 20px;
  }

  .content-title {
    font-size: 22px;
  }
}