:root{
  --brick:#a94436; /* 砖红 */
  --sand:#f7efe6; /* 砂岩白 */
  --ink:#222;
  --muted:#6b6b6b;
  --border:rgba(0,0,0,0.06);
  --max-width:1280px;
}
html,body{height:100%;}
*{box-sizing:border-box}
body{
  margin:0;
  color:var(--ink);
  background:var(--sand);
  font-family: -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,"Noto Sans",sans-serif;
  line-height:1.6;
  -webkit-font-smoothing:antialiased;
}
a{color:inherit; text-decoration:none}
.topbar{border-bottom:1px solid var(--border); background:#fff;}
.toolbar{max-width:var(--max-width); margin:0 auto; padding:12px 20px; display:flex; align-items:center; gap:16px;}
.brand{font-weight:700; color:var(--brick); font-size:18px; border-right:1px solid var(--border); padding-right:12px}
.breadcrumbs{display:flex; align-items:center; gap:8px; color:var(--muted); font-size:13px}
.breadcrumbs a{color:var(--muted)}
.breadcrumbs .sep{opacity:0.6}
.ad-holder{margin-left:auto}
.ad-top{font-size:13px; color:var(--muted)}
.index-nav{background:transparent; padding:8px 20px; border-top:1px solid var(--border)}
.index-nav ul{list-style:none; margin:0; padding:0; display:flex; gap:18px; flex-wrap:wrap}
.index-nav li{font-size:13px; color:var(--muted)}

.page-wrapper{padding:20px 12px 48px}
.layout-grid{display:block; max-width:var(--max-width); margin:0 auto}

/* Article common */
.article{background:transparent; padding:12px}
.title-strip{display:block; padding:8px 0 6px}
.title-strip h1{
  margin:0; font-size:24px; font-weight:800; letter-spacing:-0.02em; color:var(--ink); text-align:left; max-width:760px;
  position:relative; padding-left:6px;
}
/* 横线构图：粗细线 */
.title-strip h1::before{content:""; display:block; height:4px; width:44px; background:var(--brick); margin-bottom:8px}
.title-strip h1::after{content:""; display:block; height:1px; background:var(--border); margin-top:10px; width:100px}

.meta{margin-top:10px; color:var(--muted); font-size:13px; display:flex; gap:18px; align-items:center}
.summary{margin:14px 0; padding:12px; background:rgba(169,68,54,0.04); border-left:3px solid var(--brick);}
.content{color:var(--ink); font-size:16px; background:transparent}
.content p{margin:0 0 14px}

.faq h2{font-size:16px; margin:20px 0 8px; color:var(--ink); font-weight:700}
/* 视觉签名：章节标题带短编号线（不生成编号） */
.faq h2::before{content:""; display:inline-block; width:34px; height:6px; background:var(--brick); vertical-align:middle; margin-right:10px}
.faq-list details{border-top:1px solid var(--border); padding:10px 0}
.faq-list summary{cursor:pointer; font-weight:600}

.sidebar{display:none}
.related h3{font-size:14px; margin:0 0 8px; font-weight:700}
.related-list{font-size:14px; color:var(--muted)}
.kw-inline{font-size:13px; color:var(--muted); padding-top:8px}

.site-footer{border-top:1px solid var(--border); padding:18px 10px; background:#fff;}
.site-footer .foot-meta{max-width:var(--max-width); margin:8px auto 0; color:var(--muted); font-size:13px}
.ad-middle, .ad-bottom{padding:12px 0; color:var(--muted); font-size:13px}

/* Desktop layout: 中轴与注释栏 */
@media (min-width:1024px){
  .page-wrapper{padding:28px 0 64px}
  .layout-grid{display:grid; grid-template-columns: 1fr minmax(560px,760px) 320px 1fr; column-gap:28px; align-items:start}
  .article{grid-column:2 / 3; padding:18px 24px}
  .sidebar{grid-column:3 / 4; display:block; padding:18px 20px; border-left:1px solid var(--border); background:#fff;}
  .sidebar section{margin-bottom:18px}
  .title-strip h1{font-size:28px; max-width:640px}
  /* 保持整体克制对称，文章沿中轴展开，侧栏作为注释栏 */
  .summary{max-width:680px}
  /* 当页面较宽时控制容器范围 */
  .layout-grid{max-width:var(--max-width);}
  /* 防止正文受窄小手机宽度限制 */
  .article .content{font-size:17px}
}

/* Mobile layout: 单列左对齐 */
@media (max-width:767px){
  .toolbar{padding:10px 14px}
  .brand{font-size:16px}
  .index-nav ul{gap:12px}
  .layout-grid{display:block; padding:0 12px}
  .article{padding:8px 0}
  .title-strip h1{font-size:20px}
  .title-strip h1::before{width:28px; height:3px}
  .title-strip h1::after{width:60px}
  .meta{flex-direction:column; gap:6px; align-items:flex-start}
  .summary{padding:10px}
  .content{font-size:15px}
  /* 侧栏下移为区块（不固定） */
  .sidebar{display:block; border-left:none; background:transparent; padding:0; margin-top:20px}
  .related-list, .kw-inline{padding:8px 0}
  .ad-top{font-size:12px}
  .ad-holder{margin-left:0}
  /* 确保在320px无横向滚动 */
  body, .page-wrapper, .layout-grid, .article, .sidebar{min-width:0}
}

/* 中间尺寸（768-1023）做平衡 */
@media (min-width:768px) and (max-width:1023px){
  .layout-grid{padding:0 10px}
  .title-strip h1{font-size:22px}
  .layout-grid{max-width:960px}
  .sidebar{display:block; border-left:1px solid var(--border); padding-left:16px}
}

/* 可访问性与可读性调整 */
h1,h2,h3,h4{color:var(--ink)}
button,summary{cursor:pointer}