:root {
  --bg: #ffffff;
  --fg: #1f2328;
  --muted: #59636e;
  --link: #0969da;
  --code-bg: #f6f8fa;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1117;
    --fg: #e6edf3;
    --muted: #9198a1;
    --link: #4493f8;
    --code-bg: #151b23;
  }
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: system-ui, -apple-system, "Hiragino Sans", "Noto Sans JP", sans-serif;
  line-height: 1.8;
}

main {
  max-width: 720px;
  margin: 0 auto;
  padding: 32px 16px 64px;
}

h1 { font-size: 1.6rem; line-height: 1.4; }
h2 { font-size: 1.15rem; margin-top: 2em; }
a { color: var(--link); }
code { background: var(--code-bg); padding: 0.1em 0.4em; border-radius: 4px; }