:root {
  color-scheme: light dark;
  --bg: #f6f7f9;
  --card: #ffffff;
  --text: #111111;
  --muted: #4a4a4a;
  --border: #d5d8de;
  --accent: #0b5cab;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1114;
    --card: #181b20;
    --text: #f5f5f5;
    --muted: #c4c4c4;
    --border: #3a3f47;
    --accent: #7eb6ff;
  }
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
}
header, main, footer { max-width: 760px; margin: 0 auto; padding: 24px 16px; }
header h1 { margin: 0 0 8px; font-size: 1.7rem; }
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
  margin: 16px 0;
}
nav a, a { color: var(--accent); }
.muted { color: var(--muted); }
footer { font-size: 0.9rem; }