:root{
  --bg:#ffffff;
  --ink:#2b2b2b; /* 石墨灰 */
  --muted:#6b6b6b;
  --accent:#c9a600; /* 芥末黄 */
  --max-width:1320px; /* 在1120-1440之间 */
  --min-width:1120px;
  --rail-width:320px; /* 约4/12 */
  --gutter:28px;
  --serif: "Times New Roman", "Georgia", serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans CJK SC", sans-serif;
}

/* 基础布局 */
*{box-sizing:border-box}
html,body{height:100%;background:var(--bg);color:var(--ink);font-family:var(--sans);margin:0}
.container{max-width:var(--max-width);margin:0 auto;padding:20px;min-width:0}
.site-header{display:flex;align-items:center;padding:6px 0;border-bottom:1px solid #e6e6e6}
.brand{font-weight:700;color:var(--ink);text-decoration:none;font-size:18px}

.layout{display:block}
.rail{display:none}
.main{padding-top:18px}
.article{max-width:100%}
.article-header{margin-bottom:12px}
.title{font-family:var(--serif);font-size:28px;line-height:1.15;text-align:center;margin:8px 0;color:var(--ink)}
.article-meta{display:flex;gap:8px;justify-content:center;color:var(--muted);font-size:13px}
.summary{text-align:left;color:var(--muted);margin:12px 0 18px;line-height:1.5}
.article-body .content{color:var(--ink);line-height:1.8;font-size:16px}
.article-body .content p{margin:0 0 16px}

.ad{border-top:1px solid #f0f0f0;border-bottom:1px solid #f0f0f0;padding:12px 0;margin:18px 0;color:var(--muted);font-size:14px}
.site-footer{margin-top:28px;padding:14px 0;border-top:1px solid #f0f0f0;color:var(--muted);font-size:13px}

/* 相关文章列表（默认在左侧栏） */
.related-rail h4{margin:12px 0 8px;font-size:14px}
.related-list{display:grid;grid-template-columns:1fr;gap:8px}

/* FAQ 横线问答 */
.faq h3{font-size:16px;margin:18px 0 8px}
.faq-list{border-top:1px solid #e9e9e9}
.faq-list > *{padding:12px 0;border-bottom:1px solid #efefef}

/* Compact blocks for mobile (hidden on desktop) */
.compact-block{display:none}
.compact-line{font-size:13px;color:var(--muted)}

/* Desktop（宽口）规则 — 必须有 @media (min-width: 1024px) */
@media (min-width:1024px){
  .container{min-width:var(--min-width);max-width:var(--max-width);padding:36px}
  .layout{display:grid;grid-template-columns:var(--rail-width) 1fr;gap:var(--gutter);align-items:start}
  .rail{display:block;border-right:1px solid #eee;padding-right:18px}
  .rail-inner{position:sticky;top:28px}
  .index-nav .nav-title{font-size:13px;color:var(--muted);margin:0 0 8px}
  .index-nav ul{list-style:none;padding:0;margin:0 0 14px}
  .index-nav li{padding:6px 0;font-size:14px;color:var(--ink)}

  .breadcrumb{font-size:13px;color:var(--muted);margin:6px 0 12px}
  .meta-rail{font-size:13px;color:var(--muted);margin-bottom:16px}

  /* Related in left rail uses two-column summary list pattern? keep single-column snippets here, main related elsewhere */
  .related-list{display:grid;grid-template-columns:1fr;gap:10px;font-size:14px}

  /* Main column rules */
  .main{padding-left:18px}
  .title{font-size:36px;text-align:center}
  .summary{max-width:860px}

  /* Ensure article column is visually heavier than rail (reverse-rail visual weight) */
  .rail{color:var(--muted)}
  .article-body .content{font-size:17px;line-height:1.85}

  /* Related pattern in article area (if {{related}} renders here, maintain two-column small summary) */
  .related-grid{display:grid;grid-template-columns:1fr 1fr;gap:12px}

  /* Show nothing of compact mobile blocks */
  .compact-block{display:none}
}

/* Mobile（窄口）规则 — 必须有 @media (max-width: 767px) */
@media (max-width:767px){
  .container{padding:14px}
  .brand{font-size:16px}
  .layout{display:block}
  .rail{display:none}

  /* Mobile compact blocks visible around the title */
  .compact-block{display:block;margin:6px 0}
  .mobile-pretitle{margin-bottom:6px}
  .mobile-posttitle{margin-top:6px}

  /* Title composition: 居中，摘要左对齐 */
  .title{font-size:22px;margin:6px 0;text-align:center}
  .summary{text-align:left;font-size:14px;margin-bottom:10px}

  /* Content is primary reading area and follows title/meta closely */
  .article-body .content{font-size:16px;line-height:1.9}

  /* Related pattern: two-column summary list */
  .related-list{display:grid;grid-template-columns:1fr 1fr;gap:10px}

  /* Ads remain non-fixed and not overlapping */
  .ad{margin:14px 0}
}

/* Accessibility & small touches */
h1,h3,h4{margin:0}
a{color:var(--accent);text-decoration:none}
a:focus{outline:2px dashed var(--accent);outline-offset:2px}

/* Visual signature: large whitespace + tight typographic steps */
.article{padding:18px 6px}
.title{letter-spacing:0.2px}
.summary{max-width:920px}

/* Surface rules: 无圆角、细分隔线、无阴影 */
*{border-radius:0}