:root {
  --bg: #f6f7f9;
  --card: #ffffff;
  --text: #1c1d21;
  --muted: #6b6f78;
  --line: #e4e6eb;
  --accent: #2f6bff;
  --accent-soft: #eaf0ff;
  --warn: #c2410c;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #111214;
    --card: #1b1c1f;
    --text: #ececef;
    --muted: #9a9ea8;
    --line: #2c2e33;
    --accent: #6f98ff;
    --accent-soft: #1d2640;
    --warn: #fb923c;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.75 -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

header.top {
  position: sticky; top: 0; z-index: 10;
  background: color-mix(in srgb, var(--bg) 85%, transparent);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--line);
}
header.top .in {
  max-width: 820px; margin: 0 auto; padding: 12px 16px;
  display: flex; align-items: center; gap: 16px; flex-wrap: wrap;
}
.brand { font-weight: 700; color: var(--text); display: flex; align-items: center; gap: 8px; }
.brand .logo {
  width: 26px; height: 26px; border-radius: 7px; background: var(--accent);
  color: #fff; display: grid; place-items: center; font-size: 14px;
}
nav { display: flex; gap: 14px; margin-left: auto; font-size: 15px; flex-wrap: wrap; }
nav a { color: var(--muted); }
nav a.on { color: var(--text); font-weight: 600; }

main { max-width: 820px; margin: 0 auto; padding: 28px 16px 64px; }
h1 { font-size: 28px; line-height: 1.3; margin: 8px 0 6px; }
h2 { font-size: 20px; margin: 36px 0 10px; padding-top: 8px; }
h3 { font-size: 17px; margin: 22px 0 6px; }
p, li { color: var(--text); }
.meta { color: var(--muted); font-size: 14px; margin-bottom: 20px; }
.card {
  background: var(--card); border: 1px solid var(--line); border-radius: 14px;
  padding: 18px 20px; margin: 16px 0;
}
.note {
  background: var(--accent-soft); border-radius: 12px; padding: 14px 18px; margin: 16px 0;
}
.note b { color: var(--accent); }
table { width: 100%; border-collapse: collapse; font-size: 15px; margin: 12px 0; }
th, td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--line); vertical-align: top; }
th { color: var(--muted); font-weight: 600; font-size: 14px; }
.tablewrap { overflow-x: auto; background: var(--card); border: 1px solid var(--line); border-radius: 14px; }
.tablewrap table { margin: 0; }
.toc { columns: 2; column-gap: 24px; padding-left: 18px; }
@media (max-width: 560px) { .toc { columns: 1; } h1 { font-size: 24px; } }
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 14px; margin: 20px 0; }
.grid a.card { display: block; color: var(--text); margin: 0; transition: border-color .15s; }
.grid a.card:hover { border-color: var(--accent); text-decoration: none; }
.grid a.card b { display: block; font-size: 17px; margin-bottom: 4px; }
.grid a.card span { color: var(--muted); font-size: 14px; }
.hero { padding: 24px 0 8px; }
.hero p { color: var(--muted); font-size: 17px; margin: 0; }
kbd, .tag {
  display: inline-block; font: inherit; font-size: 13px; padding: 0 7px; border-radius: 6px;
  background: var(--accent-soft); color: var(--accent); line-height: 1.7;
}
footer { border-top: 1px solid var(--line); color: var(--muted); font-size: 13px; }
footer .in { max-width: 820px; margin: 0 auto; padding: 20px 16px 36px; }
footer a { color: var(--muted); }