:root {
  color-scheme: light dark;
  --bg: #ffffff;
  --surface: #f6f8fa;
  --border: #d8dee4;
  --text: #1f2328;
  --muted: #636c76;
  --accent: #0969da;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #17181a;
    --surface: #202124;
    --border: #3c4043;
    --text: #e8eaed;
    --muted: #9aa0a6;
    --accent: #8ab4f8;
  }
}

* { box-sizing: border-box; }

body {
  max-width: 760px;
  margin: 0 auto;
  padding: 48px 24px 64px;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.6 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

h1 { margin: 0 0 4px; font-size: 32px; letter-spacing: -0.02em; }
h2 { margin-top: 36px; font-size: 20px; }
p, li { color: var(--muted); }
a { color: var(--accent); }
code {
  padding: 1px 4px;
  border-radius: 4px;
  background: var(--surface);
  font-family: var(--mono);
  font-size: 0.9em;
}
.subtitle { margin: 0 0 28px; font-size: 18px; }
.card {
  padding: 18px 20px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface);
}
footer {
  margin-top: 48px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 13px;
}