:root {
  --bg: #ffffff;
  --ink: #111827;
  --muted: #6b7280;
  --line: #eceef2;
  --accent: #2563eb;
  --agent: #6d28d9;
  --reviewer: #0f766e;
  --human: #b45309;
  --system: #64748b;
  --pm: #db2777;
  --ok: #15803d;
  --radius: 10px;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  line-height: 1.7;
  font-size: 15px;
  padding-bottom: 64px;
}
.wrap { max-width: 1080px; margin: 0 auto; padding: 0 32px; }
.hidden { display: none !important; }

/* ================= 顶栏：左侧当前页标题，右侧锚点导航 ================= */
.topbar {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,.9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.topbar .wrap { display: flex; align-items: center; justify-content: space-between; height: 52px; }
.topbar .brand { font-weight: 800; font-size: 15px; color: var(--ink); text-decoration: none; letter-spacing: -.01em; }
.topbar .brand span { color: var(--muted); font-weight: 500; font-size: 13px; margin-left: 6px; }
.topbar .nav-links { display: flex; gap: 20px; }
.topbar .nav-links a { color: var(--muted); text-decoration: none; font-size: 13px; font-weight: 600; }
.topbar .nav-links a:hover { color: var(--accent); }
.topbar .nav-links a.nav-demo { color: var(--accent); font-weight: 700; }

/* ================= 底部导航：5 个平级页面 ================= */
.site-nav {
  position: fixed; left: 0; right: 0; bottom: 0; z-index: 90;
  background: rgba(255,255,255,.92); backdrop-filter: blur(10px);
  border-top: 1px solid var(--line);
  padding: 9px 0 11px;
}
.site-nav .wrap { display: flex; justify-content: center; gap: 6px; }
.site-nav a {
  display: flex; flex-direction: column; align-items: center; gap: 4px;
  text-decoration: none; color: var(--muted); font-size: 11px;
  padding: 2px 8px; border-radius: 8px; transition: background .2s, color .2s;
}
.site-nav a:hover { background: #f1f5f9; }
.site-nav a .bar { width: 26px; height: 3px; border-radius: 2px; background: #d7dce3; transition: background .3s; }
.site-nav a.on { color: var(--accent); font-weight: 700; }
.site-nav a.on .bar { background: var(--accent); }

/* ================= 通用 section 标题 ================= */
.sec { padding: 48px 0 8px; }
.sec-head { margin-bottom: 26px; }
.sec-head .no { color: var(--accent); font-size: 13px; font-weight: 700; letter-spacing: .1em; }
.sec-head h2 { font-size: 26px; font-weight: 800; letter-spacing: -0.01em; margin-top: 6px; }
.sec-head p { color: var(--muted); margin-top: 8px; }

/* ================= 子页头部 ================= */
.loop-head { padding: 48px 0 4px; }
.loop-head h1 { font-size: 30px; margin: 14px 0 10px; letter-spacing: -0.01em; }
.loop-head .sub { color: var(--muted); font-size: 15px; }

footer { padding: 36px 0 32px; text-align: center; color: var(--muted); font-size: 13px; }
footer a { color: var(--accent); text-decoration: none; }

@media (max-width: 760px) {
  .site-nav a { font-size: 10px; padding: 2px 5px; }
  .site-nav a .bar { width: 18px; }
  .topbar .nav-links { display: none; }
}