:root {
  --bg: #f7f8fa;
  --surface: #ffffff;
  --text: #18212f;
  --muted: #4d5869;
  --accent: #2f5bea;
  --border: #dde2ea;
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f141c;
    --surface: #18202c;
    --text: #e8edf5;
    --muted: #a4afc0;
    --accent: #8aa6ff;
    --border: #2a3444;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.6 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}
main { max-width: 760px; margin: 0 auto; padding: 40px 16px 64px; }
header { margin-bottom: 32px; }
h1 { font-size: 2rem; line-height: 1.2; margin: 0 0 8px; }
h2 { font-size: 1.25rem; margin: 36px 0 8px; }
h3 { font-size: 1.05rem; margin: 24px 0 4px; }
p, li { color: var(--text); }
.lead { font-size: 1.15rem; color: var(--muted); margin: 0; }
.muted { color: var(--muted); }
a { color: var(--accent); }
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 20px;
  margin: 16px 0;
}
.button {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  text-decoration: none;
  font-weight: 600;
  padding: 10px 18px;
  border-radius: 8px;
}
@media (prefers-color-scheme: dark) { .button { color: #0f141c; } }
nav { display: flex; gap: 16px; flex-wrap: wrap; font-size: 0.95rem; }
footer { margin-top: 48px; padding-top: 16px; border-top: 1px solid var(--border); font-size: 0.9rem; color: var(--muted); }
code { font-size: 0.92em; }