:root {
  --bg: #f6f5f2; --fg: #1d1d1f; --muted: #6e6e73; --line: #e3e1dc;
  --card: #ffffff; --accent: #2f7d4f; --link: #1f6fd1;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #16171b; --fg: #f2f2f4; --muted: #9a9aa2; --line: #2b2c33;
          --card: #1e1f25; --accent: #5fc98a; --link: #7ab4ff; color-scheme: dark; }
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--fg);
  font: 17px/1.6 -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", Arial, sans-serif; }
main { max-width: 680px; margin: 0 auto; padding: 56px 20px 80px; }
a { color: var(--link); }
header { display: flex; align-items: center; gap: 16px; margin-bottom: 8px; }
header img { width: 64px; height: 64px; border-radius: 14px; }
h1 { font-size: 34px; line-height: 1.15; margin: 0; letter-spacing: -0.02em; }
h2 { font-size: 20px; margin: 40px 0 8px; letter-spacing: -0.01em; }
.lede { color: var(--muted); font-size: 19px; margin: 12px 0 28px; }
.rail { display: flex; gap: 5px; margin: 28px 0; }
.rail span { width: 10px; height: 26px; border-radius: 3px; background: var(--line); }
.rail span.done { background: var(--accent); }
.card { background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 20px 22px; margin: 16px 0; }
dl { margin: 0; } dt { font-weight: 600; margin-top: 14px; } dt:first-child { margin-top: 0; }
dd { margin: 2px 0 0; color: var(--muted); }
kbd { font: 14px ui-monospace, "SF Mono", Menlo, monospace; background: var(--card); border: 1px solid var(--line);
  border-radius: 6px; padding: 1px 6px; }
nav { display: flex; gap: 20px; flex-wrap: wrap; margin-top: 48px; padding-top: 20px; border-top: 1px solid var(--line);
  color: var(--muted); font-size: 15px; }