: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: system-ui, -apple-system, "Hiragino Sans", "Noto Sans JP", sans-serif; line-height: 1.8; }
main { max-width: 720px; margin: 0 auto; padding: 40px 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-top: 16px; border-top: 1px solid var(--line); }
p, li { overflow-wrap: anywhere; }
a { color: var(--link); }
.muted { color: var(--muted); font-size: 0.9rem; }
footer { margin-top: 48px; padding-top: 16px; border-top: 1px solid var(--line); }