:root {
  --bg: #f6f7fb;
  --surface: #ffffff;
  --ink: #1c1d22;
  --muted: #6b6f7b;
  --line: #e4e6ee;
  --accent: #4f5bd5;
  --callout: #eef0fd;
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1116;
    --surface: #181b22;
    --ink: #eceef3;
    --muted: #9aa0ad;
    --line: #2a2e38;
    --accent: #8d96ff;
    --callout: #1f2333;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.75 -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  -webkit-text-size-adjust: 100%;
}
main {
  max-width: 760px;
  margin: 0 auto;
  padding: 40px 20px 64px;
}
.topbar { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.topbar a { min-height: 44px; display: inline-flex; align-items: center; }
.brand { margin: 0; font-weight: 700; font-size: 20px; letter-spacing: .02em; color: var(--ink) !important; }
h1 { margin: 8px 0 4px; font-size: 30px; line-height: 1.3; }
.meta { margin: 0 0 28px; color: var(--muted); font-size: 14px; }
h2 { margin: 36px 0 10px; padding-top: 20px; border-top: 1px solid var(--line); font-size: 20px; }
h3 { margin: 22px 0 6px; font-size: 17px; }
p, li { overflow-wrap: anywhere; }
ul { padding-left: 1.3em; }
li { margin: 4px 0; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
.callout { background: var(--callout); border-radius: 14px; padding: 14px 16px; }
.footer { margin-top: 40px; padding-top: 20px; border-top: 1px solid var(--line); color: var(--muted); font-size: 14px; }