:root {
  --bg: #070b16;
  --bg-soft: #0d1426;
  --bg-card: #0f1830;
  --bg-elev: #131f3d;
  --line: #1e2c4d;
  --line-soft: #16213d;
  --txt: #e6edf7;
  --txt-dim: #9fb0cc;
  --txt-mute: #6b7c9c;
  --accent: #38bdf8;
  --accent-2: #6366f1;
  --accent-3: #22d3ee;
  --ok: #34d399;
  --warn: #fbbf24;
  --radius: 14px;
  --maxw: 1180px;
  --h2-inset: 16px;
  --font: "PingFang SC", "Microsoft YaHei", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono: "SFMono-Regular", "JetBrains Mono", Consolas, monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: radial-gradient(1200px 600px at 80% -10%, #11203f 0%, var(--bg) 55%) fixed, var(--bg);
  color: var(--txt);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-3); }
img { max-width: 100%; display: block; }
.container { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }

/* ── Header ───────────────────────────── */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 50;
  background: rgba(7, 11, 22, 0.78);
  backdrop-filter: saturate(160%) blur(12px);
  border-bottom: 1px solid var(--line);
}
.nav { display: flex; align-items: center; gap: 22px; height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; color: var(--txt); font-size: 17px; letter-spacing: .2px; }
.brand .dot { width: 11px; height: 11px; border-radius: 50%; background: linear-gradient(135deg, var(--accent), var(--accent-2)); box-shadow: 0 0 14px var(--accent); }
.nav-links { display: flex; align-items: center; gap: 4px; margin-left: auto; }
.nav-item { position: relative; }
.nav-item > a, .nav-trigger {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 8px 12px; border-radius: 10px; color: var(--txt-dim);
  font-size: 14.5px; background: none; border: 0; cursor: pointer; font-family: inherit;
}
.nav-item > a:hover, .nav-trigger:hover { color: var(--txt); background: var(--bg-elev); }
.nav-trigger .caret { transition: transform .2s; font-size: 10px; opacity: .7; }
.nav-item.open .caret { transform: rotate(180deg); }
.dropdown {
  position: absolute; top: 46px; left: 0; min-width: 220px;
  background: var(--bg-card); border: 1px solid var(--line); border-radius: 12px;
  padding: 8px; display: none; box-shadow: 0 18px 50px rgba(0,0,0,.5);
}
.nav-item.open .dropdown { display: block; }
.dropdown a { display: block; padding: 8px 10px; border-radius: 8px; color: var(--txt-dim); font-size: 14px; }
.dropdown a:hover { background: var(--bg-elev); color: var(--txt); }
.nav-toggle { display: none; margin-left: auto; background: none; border: 0; color: var(--txt); font-size: 22px; cursor: pointer; }

/* ── Breadcrumb ───────────────────────── */
.breadcrumb { font-size: 13px; color: var(--txt-mute); margin: 18px 0 6px; padding-left: var(--h2-inset); }
.breadcrumb a { color: var(--txt-dim); }
.breadcrumb .sep { margin: 0 8px; color: var(--line); }
.breadcrumb .cur { color: var(--txt); }

/* ── Layout ───────────────────────────── */
main { padding-top: 64px; }
.page-wrap { max-width: 920px; margin: 0 auto; padding: 40px 24px 80px; }
.list-layout { max-width: var(--maxw); margin: 0 auto; padding: 30px 24px 80px; display: grid; grid-template-columns: 220px 1fr; gap: 36px; }
.article-layout { max-width: var(--maxw); margin: 0 auto; padding: 24px 24px 90px; display: grid; grid-template-columns: minmax(0, 760px) 240px; gap: 36px; justify-content: center; }
.article-main { min-width: 0; }

/* ── Hero (home) ──────────────────────── */
.hero { padding: 90px 0 40px; }
.hero h1 { font-size: clamp(30px, 5vw, 50px); line-height: 1.15; margin: 0 0 18px; letter-spacing: -.5px; }
.hero h1 .grad { background: linear-gradient(120deg, var(--accent), var(--accent-2)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero p.lead { color: var(--txt-dim); font-size: 18px; max-width: 720px; }
.hero .cta-row { display: flex; gap: 14px; flex-wrap: wrap; margin-top: 26px; }
.btn { display: inline-flex; align-items: center; gap: 8px; padding: 12px 20px; border-radius: 11px; font-weight: 600; font-size: 15px; border: 1px solid var(--line); background: var(--bg-elev); color: var(--txt); cursor: pointer; }
.btn.primary { background: linear-gradient(120deg, var(--accent), var(--accent-2)); border: 0; color: #04121f; }
.btn:hover { filter: brightness(1.08); color: var(--txt); }

/* ── Cards / grids ────────────────────── */
.section { padding: 34px 0; }
.section h2.title { font-size: 24px; margin: 0 0 18px; }
.grid { display: grid; gap: 18px; }
.grid.cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid.cols-2 { grid-template-columns: repeat(2, 1fr); }
.card { background: var(--bg-card); border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; transition: border-color .2s, transform .2s; }
.card:hover { border-color: var(--accent); transform: translateY(-2px); }
.card h3 { margin: 0 0 8px; font-size: 17px; }
.card p { margin: 0; color: var(--txt-dim); font-size: 14.5px; }
.card .meta { margin-top: 12px; font-size: 12.5px; color: var(--txt-mute); }
.tag-row { margin-top: 10px; display: flex; flex-wrap: wrap; gap: 6px; }
.tag-text { font-size: 12px; color: var(--txt-dim); background: var(--bg-elev); border: 1px solid var(--line); border-radius: 999px; padding: 2px 10px; }

/* ── Article body ─────────────────────── */
.article-main h1 { font-size: 30px; line-height: 1.25; margin: 10px 0 14px; letter-spacing: -.3px; }
.summary-block { background: linear-gradient(180deg, var(--bg-elev), var(--bg-card)); border: 1px solid var(--line); border-left: 3px solid var(--accent); border-radius: 12px; padding: 16px 18px; color: var(--txt-dim); font-size: 15.5px; margin-bottom: 16px; }
.kw-row { font-size: 13px; color: var(--txt-mute); margin-bottom: 10px; }
.kw-row b { color: var(--txt-dim); font-weight: 600; }
.update-line { font-size: 12.5px; color: var(--txt-mute); margin-bottom: 18px; }
.article-main h2 { font-size: 22px; margin: 34px 0 12px; padding-top: 8px; border-top: 1px solid var(--line-soft); scroll-margin-top: 80px; }
.article-main h3 { font-size: 17px; margin: 22px 0 10px; scroll-margin-top: 80px; }
.article-main p { margin: 0 0 14px; }
.article-main ul, .article-main ol { margin: 0 0 14px; padding-left: 22px; }
.article-main li { margin-bottom: 6px; }
.article-main blockquote { margin: 16px 0; padding: 12px 16px; border-left: 3px solid var(--accent-2); background: var(--bg-soft); border-radius: 0 10px 10px 0; color: var(--txt-dim); }
.conclusion { background: var(--bg-soft); border: 1px solid var(--line); border-radius: 12px; padding: 16px 18px; margin: 18px 0; }
.conclusion h4 { margin: 0 0 8px; font-size: 15px; color: var(--accent); }
.conclusion ol { margin: 0; padding-left: 20px; }

/* tables */
table.data { width: 100%; border-collapse: collapse; margin: 14px 0 18px; font-size: 14px; }
table.data th, table.data td { border: 1px solid var(--line); padding: 9px 12px; text-align: left; }
table.data th { background: var(--bg-elev); color: var(--txt); font-weight: 600; }
table.data tr:nth-child(even) td { background: rgba(255,255,255,.02); }

/* FAQ */
.faq details { border: 1px solid var(--line); border-radius: 12px; padding: 0; margin: 10px 0; background: var(--bg-card); overflow: hidden; }
.faq details summary { cursor: pointer; padding: 13px 16px; font-weight: 600; font-size: 15px; list-style: none; display: flex; justify-content: space-between; align-items: center; }
.faq details summary::-webkit-details-marker { display: none; }
.faq details summary::after { content: "+"; color: var(--accent); font-size: 20px; }
.faq details[open] summary::after { content: "−"; }
.faq details .faq-a { padding: 0 16px 14px; color: var(--txt-dim); font-size: 14.5px; }
.faq h2 { border: 0; margin-top: 36px; }

/* related */
.related { margin-top: 40px; border-top: 1px solid var(--line); padding-top: 20px; }
.related h2 { border: 0; }
.related ul { list-style: none; padding: 0; margin: 0; }
.related li { padding: 10px 0; border-bottom: 1px solid var(--line-soft); }
.related li a { font-weight: 600; }
.related li .why { display: block; color: var(--txt-mute); font-size: 13px; margin-top: 3px; }

/* TOC */
.toc-aside { position: sticky; top: 84px; align-self: start; max-height: calc(100vh - 110px); overflow-y: auto; }
.toc { background: var(--bg-card); border: 1px solid var(--line); border-radius: 12px; padding: 16px; }
.toc h4 { margin: 0 0 10px; font-size: 13px; color: var(--txt-mute); text-transform: uppercase; letter-spacing: .08em; }
.toc a { display: block; padding: 6px 0; color: var(--txt-dim); font-size: 13.5px; border-left: 2px solid transparent; padding-left: 10px; }
.toc a:hover { color: var(--txt); border-left-color: var(--accent); }

/* category list */
.cat-side { position: sticky; top: 84px; align-self: start; }
ul.category-list { list-style: none; margin: 0; padding: 0; }
ul.category-list li a { display: block; padding: 10px 14px; border-radius: 10px; color: var(--txt-dim); border: 1px solid transparent; font-size: 14.5px; }
ul.category-list li a:hover, ul.category-list li a.active { background: var(--bg-elev); color: var(--txt); border-color: var(--line); }

/* ── Footer ───────────────────────────── */
.site-footer { border-top: 1px solid var(--line); background: var(--bg-soft); padding: 40px 0 30px; margin-top: 40px; }
.footer-grid { display: grid; grid-template-columns: 1.5fr 1fr 1fr; gap: 30px; }
.footer-grid h4 { font-size: 14px; color: var(--txt); margin: 0 0 12px; }
.footer-grid a { display: block; color: var(--txt-dim); font-size: 14px; padding: 4px 0; }
.footer-grid p { color: var(--txt-mute); font-size: 13.5px; }
.footer-bottom { border-top: 1px solid var(--line-soft); margin-top: 26px; padding-top: 18px; color: var(--txt-mute); font-size: 13px; }

/* ── Floating capsule ─────────────────── */
.float-capsule { position: fixed; right: 20px; top: 50%; transform: translateY(-50%); z-index: 60; display: flex; flex-direction: column; gap: 12px; }
.cap-btn { width: 50px; height: 50px; border-radius: 999px; background: var(--bg-card); border: 1px solid var(--line); color: var(--txt); display: flex; flex-direction: column; align-items: center; justify-content: center; cursor: pointer; font-size: 18px; gap: 2px; box-shadow: 0 10px 30px rgba(0,0,0,.45); transition: border-color .2s, transform .2s; }
.cap-btn span { font-size: 9px; letter-spacing: .04em; }
.cap-btn:hover { border-color: var(--accent); transform: scale(1.05); color: var(--accent); }

/* wechat modal */
.modal-mask { position: fixed; inset: 0; background: rgba(3,6,14,.72); display: none; align-items: center; justify-content: center; z-index: 80; backdrop-filter: blur(3px); }
.modal-mask.show { display: flex; }
.modal-card { position: relative; background: var(--bg-card); border: 1px solid var(--line); border-radius: 16px; padding: 14px; }
.modal-card img { width: 300px; height: 500px; object-fit: contain; border-radius: 10px; }
.modal-close { position: absolute; top: -14px; right: -14px; width: 34px; height: 34px; border-radius: 50%; background: var(--bg-elev); border: 1px solid var(--line); color: var(--txt); cursor: pointer; font-size: 18px; line-height: 1; }

/* hero stats */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; margin-top: 40px; }
.stat { background: var(--bg-card); border: 1px solid var(--line); border-radius: 12px; padding: 18px; }
.stat .n { font-size: 26px; font-weight: 700; color: var(--accent); }
.stat .l { font-size: 13px; color: var(--txt-mute); margin-top: 4px; }

/* ── Responsive ───────────────────────── */
@media (max-width: 1080px) {
  .article-layout { grid-template-columns: minmax(0,1fr); }
  .toc-aside { display: none; }
  .list-layout { grid-template-columns: 1fr; }
  .cat-side { position: static; }
}
@media (max-width: 860px) {
  .nav-links { display: none; position: absolute; top: 64px; left: 0; right: 0; flex-direction: column; align-items: stretch; background: var(--bg-card); border-bottom: 1px solid var(--line); padding: 10px; gap: 2px; }
  .nav-links.open { display: flex; }
  .nav-item { width: 100%; }
  .nav-item > a, .nav-trigger { width: 100%; justify-content: space-between; }
  .dropdown { position: static; box-shadow: none; border: 0; padding: 0 0 6px 12px; min-width: 0; }
  .nav-toggle { display: block; }
  .grid.cols-3, .grid.cols-2 { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .stats { grid-template-columns: repeat(2, 1fr); }
}