:root {
  --blue: #2b6cf6;
  --ink: #0f172a;
  --muted: #64748b;
  --line: #e2e8f0;
  --bg: #f8fafc;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei UI", "PingFang SC", sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}
.wrap { max-width: 820px; margin: 0 auto; padding: 0 24px; }
nav.top { border-bottom: 1px solid var(--line); background: #fff; }
nav.top .wrap { display: flex; align-items: center; gap: 12px; padding: 14px 24px; }
nav.top img { width: 26px; height: 26px; }
nav.top a { color: var(--muted); text-decoration: none; font-size: 14px; }
nav.top a:hover { color: var(--blue); }
nav.top .brand { color: var(--ink); font-weight: 700; font-size: 15px; }
article { padding: 40px 0 60px; }
h1 { font-size: 34px; line-height: 1.35; margin: 0 0 12px; letter-spacing: -0.3px; }
.meta { color: #94a3b8; font-size: 13px; margin-bottom: 28px; }
h2 { font-size: 23px; margin: 40px 0 12px; }
h3 { font-size: 18px; margin: 26px 0 8px; }
p { margin: 12px 0; }
ul, ol { padding-left: 24px; }
li { margin: 8px 0; }
code { background: #eef2f7; padding: 2px 6px; border-radius: 5px; font-size: 13px; }
a { color: var(--blue); }
.cta {
  margin: 32px 0; padding: 22px 24px; border-radius: 12px; background: #fff;
  border: 1px solid var(--line); box-shadow: 0 6px 20px rgba(15,23,42,.05);
}
.cta h3 { margin: 0 0 8px; }
.btn {
  display: inline-block; margin-top: 8px; padding: 10px 22px; border-radius: 9px;
  background: var(--blue); color: #fff; text-decoration: none; font-weight: 600; font-size: 15px;
}
.btn:hover { background: #1d4ed8; }
.note { color: var(--muted); font-size: 14px; border-left: 3px solid var(--line); padding-left: 14px; }
footer { border-top: 1px solid var(--line); color: #94a3b8; font-size: 13px; padding: 28px 0 50px; }
footer a { color: var(--muted); }