:root {
  --bg: #ffffff; --text: #121921; --muted: #5b6573; --accent: #0a7cff;
  --card: #f4f6f9; --rule: #e3e7ec;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #121921; --text: #eef1f5; --muted: #9aa5b3; --accent: #3d9bff; --card: #1b2430; --rule: #2a3442; }
}
* { box-sizing: border-box; }
body {
  margin: 0; background: var(--bg); color: var(--text);
  font: 17px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
}
main { max-width: 720px; margin: 0 auto; padding: 40px 20px 64px; }
header { text-align: center; margin-bottom: 32px; }
header img { width: min(320px, 80%); height: auto; }
nav { margin-top: 12px; font-size: 15px; }
nav a { margin: 0 10px; }
h1 { font-size: 30px; line-height: 1.2; margin: 0 0 4px; }
h2 { font-size: 21px; margin: 36px 0 8px; }
h3 { font-size: 17px; margin: 24px 0 4px; }
p, li { color: var(--text); }
.muted { color: var(--muted); font-size: 15px; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
.summary { background: var(--card); border-radius: 12px; padding: 16px 20px; margin: 20px 0; }
.summary ul { margin: 0; padding-left: 20px; }
kbd {
  font: 14px ui-monospace, SFMono-Regular, Menlo, monospace; background: var(--card);
  border: 1px solid var(--rule); border-radius: 5px; padding: 1px 6px;
}
footer { margin-top: 48px; padding-top: 16px; border-top: 1px solid var(--rule); text-align: center; }