:root {
  --bg: #0a0e14;
  --surface: #111824;
  --surface-2: #18212f;
  --surface-3: #1f2a3a;
  --border: #243043;
  --border-strong: #324056;
  --text: #cbd5e1;
  --text-strong: #eef3f9;
  --muted: #8290a6;
  --accent: #2dd4bf;
  --accent-2: #38bdf8;
  --accent-warm: #fbbf24;
  --danger: #f87171;
  --h2-inset: 16px;
  --page-inset: 48px;
  --maxw: 1200px;
  --content-w: 760px;
  --toc-w: 240px;
  --nav-h: 64px;
  --radius: 10px;
  font-synthesis: none;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", sans-serif;
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent-2); text-decoration: none; }
a:hover { color: var(--accent); }
img { max-width: 100%; height: auto; }
.container { max-width: var(--maxw); margin: 0 auto; padding-left: 24px; padding-right: 24px; }

/* ===== 顶部固定导航 ===== */
.site-nav {
  position: fixed; top: 0; left: 0; right: 0; height: var(--nav-h);
  background: rgba(10,14,20,0.86); backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  z-index: 100; display: flex; align-items: center;
}
.site-nav .nav-inner { max-width: var(--maxw); margin: 0 auto; width: 100%; padding: 0 24px; display: flex; align-items: center; gap: 24px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; color: var(--text-strong); font-size: 17px; white-space: nowrap; }
.brand .logo-mark { width: 30px; height: 30px; border-radius: 7px; background: linear-gradient(135deg, var(--accent), var(--accent-2)); display: inline-flex; align-items: center; justify-content: center; color: #06121a; font-weight: 800; font-size: 15px; }
.brand .cn { color: var(--muted); font-weight: 500; font-size: 13px; }
.nav-links { display: flex; align-items: center; gap: 4px; margin-left: auto; flex-wrap: wrap; }
.nav-links > .nav-item { position: relative; }
.nav-links a.nav-link { display: inline-flex; align-items: center; gap: 5px; padding: 8px 12px; color: var(--text); border-radius: 8px; font-size: 15px; }
.nav-links a.nav-link:hover, .nav-links a.nav-link.active { background: var(--surface-2); color: var(--text-strong); }
.nav-item .sub-menu { display: none; position: absolute; top: 100%; left: 0; min-width: 180px; background: var(--surface); border: 1px solid var(--border); border-radius: 10px; padding: 6px; box-shadow: 0 12px 30px rgba(0,0,0,.45); z-index: 110; }
.nav-item:hover .sub-menu { display: block; }
.sub-menu a { display: block; padding: 8px 12px; border-radius: 7px; color: var(--text); font-size: 14px; }
.sub-menu a:hover { background: var(--surface-2); color: var(--accent); }
.nav-toggle { display: none; margin-left: auto; background: var(--surface-2); border: 1px solid var(--border); color: var(--text-strong); width: 40px; height: 40px; border-radius: 9px; font-size: 18px; cursor: pointer; }

/* ===== 主体布局 ===== */
main { padding-top: calc(var(--nav-h) + 28px); padding-bottom: 64px; min-height: 60vh; }
.article-layout { display: grid; grid-template-columns: minmax(0, var(--content-w)) var(--toc-w); gap: 36px; align-items: start; }
.article-content { min-width: 0; }
.page-wrap { max-width: 820px; margin: 0 auto; }
.list-layout { display: grid; grid-template-columns: 220px minmax(0,1fr); gap: 36px; align-items: start; }

/* ===== 面包屑（与 H2 左缘严格对齐）===== */
.breadcrumb { padding-left: var(--h2-inset); margin: 0 0 18px; font-size: 13.5px; color: var(--muted); }
.breadcrumb ol { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: 6px; align-items: center; }
.breadcrumb li { display: inline-flex; align-items: center; gap: 6px; }
.breadcrumb li + li::before { content: "›"; color: var(--border-strong); }
.breadcrumb a { color: var(--muted); }
.breadcrumb a:hover { color: var(--accent); }
.breadcrumb .current { color: var(--text); }
.page-wrap .breadcrumb { padding-left: var(--page-inset); }

/* ===== 文章排版 ===== */
.article-content h1 { font-size: 30px; line-height: 1.35; color: var(--text-strong); margin: 4px 0 14px; padding-left: var(--h2-inset); letter-spacing: -.2px; }
.article-content h2 { font-size: 22px; color: var(--text-strong); margin: 34px 0 12px; padding-left: var(--h2-inset); padding-bottom: 8px; border-bottom: 1px solid var(--border); scroll-margin-top: calc(var(--nav-h) + 16px); }
.article-content h3 { font-size: 18px; color: var(--text-strong); margin: 24px 0 10px; padding-left: var(--h2-inset); }
.article-content p, .article-content li { padding-left: var(--h2-inset); }
.article-content ul, .article-content ol { padding-left: calc(var(--h2-inset) + 22px); margin: 10px 0; }
.article-content p { margin: 12px 0; }
.article-content > p:first-of-type { color: var(--text); }

/* 摘要块 */
.summary-block { margin: 0 0 20px; padding: 16px 18px 16px calc(var(--h2-inset) + 2px); background: linear-gradient(135deg, var(--surface-2), var(--surface)); border: 1px solid var(--border); border-left: 3px solid var(--accent); border-radius: var(--radius); }
.summary-block .lbl { font-size: 12px; letter-spacing: 2px; color: var(--accent); text-transform: uppercase; display: block; margin-bottom: 6px; }
.keywords-row { padding-left: var(--h2-inset); margin: 0 0 14px; font-size: 13px; color: var(--muted); }
.keywords-row .tag-text { display: inline-block; background: var(--surface-2); border: 1px solid var(--border); border-radius: 999px; padding: 2px 10px; margin: 0 6px 6px 0; color: var(--text); font-size: 12.5px; }
.update-time { padding-left: var(--h2-inset); font-size: 13px; color: var(--muted); margin: 0 0 16px; }

/* 表格（table.data） */
table.data { width: 100%; border-collapse: collapse; margin: 16px 0 16px var(--h2-inset); max-width: calc(100% - var(--h2-inset)); font-size: 14.5px; }
table.data th, table.data td { border: 1px solid var(--border); padding: 9px 12px; text-align: left; vertical-align: top; }
table.data th { background: var(--surface-3); color: var(--text-strong); font-weight: 600; }
table.data tr:nth-child(even) td { background: rgba(255,255,255,.02); }

/* 结论块 / callout */
.callout { margin: 16px 0 16px var(--h2-inset); padding: 14px 16px; background: var(--surface-2); border: 1px solid var(--border); border-radius: var(--radius); border-left: 3px solid var(--accent-warm); }
.callout .lbl { color: var(--accent-warm); font-weight: 600; display:block; margin-bottom:6px; font-size:14px; }
.callout.conclusion { border-left-color: var(--accent); }
.callout.conclusion .lbl { color: var(--accent); }
.callout.practice { border-left-color: var(--accent-2); }
.callout.practice .lbl { color: var(--accent-2); }

/* FAQ 裸 details */
.article-content details.faq-item { margin: 10px 0 10px var(--h2-inset); border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); overflow: hidden; }
.article-content details.faq-item summary { cursor: pointer; padding: 12px 16px; font-weight: 600; color: var(--text-strong); list-style: none; }
.article-content details.faq-item summary::-webkit-details-marker { display: none; }
.article-content details.faq-item summary::after { content: "+"; float: right; color: var(--accent); font-weight: 700; }
.article-content details.faq-item[open] summary::after { content: "−"; }
.article-content details.faq-item .faq-a { padding: 0 16px 14px; color: var(--text); }

/* 相关阅读 */
.related-list { margin: 18px 0 0 var(--h2-inset); padding: 0; list-style: none; }
.related-list li { padding: 10px 0; border-top: 1px solid var(--border); }
.related-list li:first-child { border-top: none; }
.related-list .why { display: block; color: var(--muted); font-size: 13px; margin-top: 2px; }

/* ===== TOC 悬浮 ===== */
.toc-aside { position: sticky; top: calc(var(--nav-h) + 20px); max-height: calc(100vh - 100px); overflow-y: auto; font-size: 14px; }
.toc-aside .toc-title { color: var(--muted); font-size: 12px; letter-spacing: 2px; text-transform: uppercase; margin-bottom: 10px; }
.toc-aside ol { list-style: none; margin: 0; padding: 0; border-left: 2px solid var(--border); }
.toc-aside li a { display: block; padding: 6px 0 6px 14px; margin-left: -2px; border-left: 2px solid transparent; color: var(--muted); }
.toc-aside li a:hover, .toc-aside li a.active { color: var(--accent); border-left-color: var(--accent); }

/* ===== 列表页分类左列 ===== */
.category-list { list-style: none; margin: 0; padding: 0; position: sticky; top: calc(var(--nav-h) + 20px); }
.category-list li a { display: block; padding: 10px 14px; border-radius: 8px; color: var(--text); border: 1px solid transparent; }
.category-list li a:hover, .category-list li a.active { background: var(--surface-2); border-color: var(--border); color: var(--text-strong); }
.cat-content h1 { font-size: 28px; color: var(--text-strong); margin: 0 0 8px; }
.card-list { display: grid; gap: 14px; margin-top: 18px; }
.card { display: block; padding: 18px; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); transition: border-color .15s, transform .15s; }
.card:hover { border-color: var(--accent); transform: translateY(-2px); }
.card h3 { margin: 0 0 6px; color: var(--text-strong); font-size: 17px; }
.card p { margin: 0; color: var(--muted); font-size: 14px; }
.card .meta { margin-top: 10px; font-size: 12.5px; color: var(--border-strong); }

/* ===== Hero / 首页 ===== */
.hero { padding: 56px 0 40px; }
.hero h1 { font-size: 40px; line-height: 1.25; color: var(--text-strong); margin: 0 0 16px; letter-spacing: -.5px; }
.hero p.lead { font-size: 18px; color: var(--muted); max-width: 720px; }
.hero .cta { margin-top: 24px; display: flex; gap: 12px; flex-wrap: wrap; }
.btn { display: inline-flex; align-items: center; gap: 8px; padding: 11px 20px; border-radius: 9px; font-weight: 600; font-size: 15px; border: 1px solid transparent; cursor: pointer; }
.btn-primary { background: linear-gradient(135deg, var(--accent), var(--accent-2)); color: #06121a; }
.btn-ghost { border-color: var(--border-strong); color: var(--text-strong); }
.section { padding: 40px 0; border-top: 1px solid var(--border); }
.section h2 { font-size: 24px; color: var(--text-strong); margin: 0 0 18px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.feature-card { padding: 22px; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); }
.feature-card h3 { margin: 0 0 8px; color: var(--text-strong); font-size: 17px; }
.feature-card p { margin: 0; color: var(--muted); font-size: 14.5px; }
.tag-row { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px; }
.tag-row .tag-text { background: var(--surface-2); border: 1px solid var(--border); border-radius: 999px; padding: 3px 12px; font-size: 13px; color: var(--text); }

/* ===== 悬浮工具胶囊 ===== */
.float-capsule { position: fixed; right: 18px; top: 50%; transform: translateY(-50%); z-index: 90; display: flex; flex-direction: column; gap: 10px; }
.float-capsule button { display: flex; flex-direction: column; align-items: center; gap: 4px; width: 56px; height: 56px; border-radius: 999px; background: var(--surface-2); border: 1px solid var(--border-strong); color: var(--text); cursor: pointer; font-size: 11px; transition: all .15s; }
.float-capsule button:hover { background: var(--accent); color: #06121a; border-color: var(--accent); }
.float-capsule button svg { width: 22px; height: 22px; }

/* 名片弹窗 */
.wechat-modal { position: fixed; inset: 0; background: rgba(4,8,12,.7); display: none; align-items: center; justify-content: center; z-index: 200; }
.wechat-modal.open { display: flex; }
.wechat-modal .modal-box { background: var(--surface); border: 1px solid var(--border-strong); border-radius: 14px; padding: 14px; position: relative; box-shadow: 0 24px 60px rgba(0,0,0,.6); }
.wechat-modal img { display: block; width: 300px; height: 500px; object-fit: contain; border-radius: 8px; }
.wechat-modal .close { position: absolute; top: -12px; right: -12px; width: 34px; height: 34px; border-radius: 50%; background: var(--surface-3); border: 1px solid var(--border-strong); color: var(--text-strong); cursor: pointer; font-size: 18px; }

/* ===== 页脚 ===== */
.site-footer { border-top: 1px solid var(--border); background: var(--surface); padding: 36px 0 28px; color: var(--muted); font-size: 14px; }
.site-footer .f-inner { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 28px; }
.site-footer h4 { color: var(--text-strong); font-size: 14px; margin: 0 0 12px; }
.site-footer a { color: var(--muted); }
.site-footer a:hover { color: var(--accent); }
.site-footer ul { list-style: none; margin: 0; padding: 0; }
.site-footer li { padding: 4px 0; }
.site-footer .copyright { max-width: var(--maxw); margin: 24px auto 0; padding: 18px 24px 0; border-top: 1px solid var(--border); font-size: 13px; }

/* ===== 响应式 ===== */
@media (max-width: 980px) {
  .article-layout { grid-template-columns: 1fr; }
  .toc-aside { display: none; }
  .list-layout { grid-template-columns: 1fr; }
  .category-list { position: static; display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 18px; }
  .grid-3 { grid-template-columns: 1fr; }
  .site-footer .f-inner { grid-template-columns: 1fr; }
}
@media (max-width: 720px) {
  .nav-links { display: none; position: absolute; top: var(--nav-h); left: 0; right: 0; background: var(--surface); border-bottom: 1px solid var(--border); flex-direction: column; padding: 12px; gap: 2px; }
  .nav-links.open { display: flex; }
  .nav-links .nav-item .sub-menu { position: static; box-shadow: none; border: none; background: transparent; padding-left: 12px; display: none; }
  .nav-links .nav-item.expanded .sub-menu { display: block; }
  .nav-toggle { display: block; }
  .hero h1 { font-size: 30px; }
  .article-content h1 { font-size: 25px; }
  :root { --h2-inset: 0px; --page-inset: 0px; }
}