:root {
  --bg: #ffffff;
  --fg: #1f2328;
  --muted: #59636e;
  --line: #d1d9e0;
  --link: #0969da;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1117;
    --fg: #e6edf3;
    --muted: #9198a1;
    --line: #3d444d;
    --link: #4493f8;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Noto Sans JP", sans-serif;
  line-height: 1.8;
}
main { max-width: 760px; margin: 0 auto; padding: 32px 16px 64px; }
h1 { font-size: 1.6rem; line-height: 1.4; margin: 0 0 8px; }
h2 { font-size: 1.15rem; margin: 32px 0 8px; padding-bottom: 4px; border-bottom: 1px solid var(--line); }
a { color: var(--link); }
nav { font-size: 0.9rem; margin-bottom: 24px; }
nav a { margin-right: 12px; }
.date, footer { color: var(--muted); font-size: 0.9rem; }
footer { margin-top: 48px; border-top: 1px solid var(--line); padding-top: 12px; }
dl { margin: 0; }
dt { font-weight: 600; margin-top: 16px; }
dd { margin: 4px 0 0; }
code { font-size: 0.9em; }