/* ============================================
   K12 Education Blog - Main Stylesheet
   ============================================ */

    :root {
      --primary-color: #007bff;
      --secondary-color: #6c757d;
      --success-color: #28a745;
      --warning-color: #ffc107;
      --danger-color: #dc3545;
      --info-color: #17a2b8;
      --light-color: #f8f9fa;
      --dark-color: #343a40;
      --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    }
    
    body {
      font-family: var(--font-family);
      line-height: 1.6;
    }
    
    .language-switch {
      margin-left: 15px;
    }
    .language-switch a {
      text-decoration: none;
      padding: 5px 10px;
      border-radius: 4px;
      transition: all 0.3s ease;
    }
    .language-switch a.active {
      background-color: var(--primary-color);
      color: white;
    }
    .language-switch a:hover:not(.active) {
      background-color: var(--light-color);
      color: var(--primary-color);
    }
    
    .visitor-count {
      font-size: 0.9em;
      color: var(--secondary-color);
    }
    
    .navbar .container {
      max-width: 1400px;
    }
    
    .main-content {
      max-width: 1400px;
      margin: 0 auto;
      padding: 1rem;
    }

    /* 导航栏响应式样式 */
    @media (max-width: 991px) {
      .navbar-collapse {
        margin-top: 1rem;
      }
      .navbar-nav {
        border-top: 1px solid rgba(0,0,0,.1);
        padding-top: 0.5rem;
      }
      .d-flex.align-items-center {
        margin-top: 0.5rem;
        padding-top: 0.5rem;
        border-top: 1px solid rgba(0,0,0,.1);
        justify-content: center;
        width: 100%;
      }
      .visitor-count {
        text-align: center;
      }
      .language-switch {
        margin-left: 10px;
      }
    }

    /* 新增响应式样式 */
    .header-container {
      display: flex;
      flex-direction: column;
      gap: 1.5rem;
      margin-bottom: 2rem;
    }
    .header-content {
      flex: 1;
    }
    .main-title {
      font-size: clamp(1.8rem, 4vw, 2.5rem);
      margin-bottom: 1rem;
      font-weight: 700;
    }
    .ad-container {
      width: 100%;
    }
    .ad-space {
      background-color: var(--light-color);
      border: 1px solid #dee2e6;
      border-radius: 4px;
      display: flex;
      align-items: center;
      justify-content: center;
      min-height: 280px;
      width: 100%;
      padding: 1rem;
      text-align: center;
    }

    /* 响应式布局 */
    @media (min-width: 768px) {
      .header-container {
        flex-direction: row;
        align-items: flex-start;
        justify-content: space-between;
      }
      .ad-container {
        width: auto;
        min-width: 300px;
        max-width: 700px;
      }
      .main-content {
        padding: 2rem;
      }
    }

    @media (min-width: 1200px) {
      .ad-container {
        width: 700px;
      }
    }
    
    /* 标题链接悬停效果 */
    .card-title a {
      text-decoration: none;
      transition: color 0.3s ease;
    }
    
    .card-title a:hover {
      color: var(--primary-color) !important;
    }
    
    /* SEO增强样式 */
    .breadcrumb {
      background-color: transparent;
      padding: 0.75rem 0;
      margin-bottom: 1rem;
    }
    
    .breadcrumb-item + .breadcrumb-item::before {
      content: ">";
      color: var(--secondary-color);
    }
    
    .article-meta {
      font-size: 0.9rem;
      color: var(--secondary-color);
      margin-bottom: 1rem;
    }
    
    .article-tags {
      margin-top: 1rem;
    }
    
    .article-tags .badge {
      margin-right: 0.5rem;
      margin-bottom: 0.5rem;
    }
    
    .related-articles {
      margin-top: 2rem;
      padding: 1.5rem;
      background-color: var(--light-color);
      border-radius: 8px;
    }
    
    .related-articles h5 {
      color: var(--primary-color);
      margin-bottom: 1rem;
    }
    
    .related-articles .card {
      border: none;
      background-color: white;
      box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    }
    
    .related-articles .card:hover {
      transform: translateY(-2px);
      box-shadow: 0 4px 8px rgba(0,0,0,0.15);
      transition: all 0.3s ease;
    }
    
    .reading-time {
      font-size: 0.8rem;
      color: var(--secondary-color);
      font-style: italic;
    }
    
    .article-stats {
      display: flex;
      gap: 1rem;
      margin-top: 1rem;
      font-size: 0.9rem;
      color: var(--secondary-color);
    }
    
    .article-stats span {
      display: flex;
      align-items: center;
      gap: 0.25rem;
    }
    
    /* 移动端优化 */
    @media (max-width: 768px) {
      .article-stats {
        flex-direction: column;
        gap: 0.5rem;
      }
      
      .related-articles {
        padding: 1rem;
      }
    }