/* ================= 全局基础样式 ================= */
    :root { --primary: #3b82f6; --bg: #f3f4f6; --text-main: #1f2937; --card-bg: #ffffff; }
    body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif; background: var(--bg); color: var(--text-main); margin: 0; line-height: 1.6; }
    a { text-decoration: none; color: inherit; transition: 0.3s; }
    
    /* 导航栏 */
    .header { background: var(--card-bg); box-shadow: 0 2px 10px rgba(0,0,0,0.05); position: sticky; top: 0; z-index: 100; }
    .nav-container { max-width: 1200px; margin: 0 auto; padding: 15px 20px; display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; }
    .logo { font-size: 24px; font-weight: bold; color: var(--primary); margin-bottom: 5px; }
    .nav-links { display: flex; flex-wrap: wrap; gap: 10px; }
    .nav-links a { padding: 6px 16px; border-radius: 20px; background: #f3f4f6; font-size: 15px; }
    .nav-links a:hover { background: var(--primary); color: #fff; }
    
    /* 文章正文区域 */
    .article-wrap { max-width: 1000px; margin: 30px auto; background: var(--card-bg); border-radius: 12px; padding: 30px 20px; box-shadow: 0 4px 10px rgba(0,0,0,0.03); box-sizing: border-box; }
    .article-title { font-size: 24px; text-align: center; margin-top: 0; margin-bottom: 15px; color: #111; line-height: 1.4; }
    .article-meta { text-align: center; color: #6b7280; font-size: 14px; margin-bottom: 30px; border-bottom: 1px dashed #e5e7eb; padding-bottom: 20px; }
    .article-meta span { margin: 0 10px; display: inline-block; }
    
    /* 图片展示区 */
    .img-viewer { text-align: center; margin-bottom: 15px; }
    .img-viewer img { max-width: 100%; height: auto; border-radius: 8px; box-shadow: 0 5px 15px rgba(0,0,0,0.1); cursor: pointer; display: block; margin: 0 auto; }
    .img-tip { text-align: center; font-size: 13px; color: #9ca3af; margin-bottom: 25px; }
    
    /* 分页按钮 */
    .page-controls { display: flex; justify-content: center; gap: 15px; margin-bottom: 40px; }
    .btn-page { padding: 10px 25px; background: #f3f4f6; border-radius: 30px; font-size: 15px; font-weight: bold; color: #374151; border: 1px solid #e5e7eb; }
    .btn-page:hover { background: var(--primary); color: #fff; border-color: var(--primary); }
    .btn-page.next { background: var(--primary); color: #fff; border-color: var(--primary); }
    .btn-page.next:hover { background: #2563eb; }

    /* ================= 新增：SEO 折叠文章模块（防错乱修正版） ================= */
    .seo-box { background: #f8fafc; border: 1px solid #e2e8f0; border-radius: 8px; padding: 25px; margin-bottom: 35px; }
    .seo-box-title { font-size: 16px; margin: 0 0 15px 0; color: #1f2937; border-left: 4px solid var(--primary); padding-left: 10px; font-weight: bold; }
    
    /* 内容包裹层：相对定位，限制高度 */
    .seo-content-wrap { position: relative; font-size: 14px; color: #4b5563; line-height: 1.8; max-height: 160px; overflow: hidden; transition: max-height 0.5s ease; }
    .seo-content-wrap p { margin: 0 0 10px 0; text-indent: 2em; text-align: justify; }
    
    /* 展开后的状态 */
    .seo-content-wrap.is-open { max-height: 3000px; /* 足够大的高度以容纳所有文字 */ }
    
    /* 内部底部渐变遮罩 */
    .seo-mask { position: absolute; bottom: 0; left: 0; width: 100%; height: 70px; background: linear-gradient(to bottom, rgba(248,250,252,0), rgba(248,250,252,1)); pointer-events: none; }
    
    /* 按钮居中层 */
    .seo-btn-wrap { text-align: center; margin-top: 15px; }
    .seo-btn { display: inline-block; padding: 6px 24px; background: #fff; border: 1px solid var(--primary); border-radius: 20px; color: var(--primary); font-size: 13px; cursor: pointer; transition: 0.3s; user-select: none; }
    .seo-btn:hover { background: var(--primary); color: #fff; }

    /* ================= 底部链接推荐矩阵 ================= */
    .text-recommend { background: #f8fafc; padding: 25px; border-radius: 8px; border: 1px solid #e2e8f0; }
    .text-recommend h3 { font-size: 16px; margin-top: 0; margin-bottom: 15px; color: #333; border-left: 4px solid var(--primary); padding-left: 10px; }
    .text-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 10px; }
    .text-grid a { display: block; padding: 8px 12px; background: #fff; border-radius: 4px; font-size: 14px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; border: 1px solid transparent; }
    .text-grid a:hover { color: var(--primary); background: #eff6ff; border-color: #bfdbfe; }
    
    /* 页脚 */
    .footer { background: #1f2937; color: #9ca3af; padding: 40px 20px 20px; font-size: 14px; margin-top: 40px; text-align: center; }
    .footer a { color: #d1d5db; margin: 0 10px; display: inline-block; margin-bottom: 10px; }
    .footer a:hover { color: #fff; }
    
    /* 移动端简单适配 */
    @media (max-width: 600px) {
      .article-wrap { padding: 20px 15px; margin: 15px auto; }
      .article-title { font-size: 20px; }
      .seo-box { padding: 15px; }
      .text-recommend { padding: 15px; }
    }