:root {
  color-scheme: light dark;
  --bg: #0f1419;
  --card: #1a2332;
  --text: #e8edf5;
  --muted: #9aa8bc;
  --accent: #5b9fd4;
  --border: #2a3548;
}
@media (prefers-color-scheme: light) {
  :root {
    --bg: #f4f7fb;
    --card: #ffffff;
    --text: #1a2332;
    --muted: #5a6a7e;
    --accent: #1a6fb5;
    --border: #d8e0ec;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}
main {
  max-width: 720px;
  margin: 0 auto;
  padding: 2rem 1.25rem 3rem;
}
h1 { margin: 0 0 0.25rem; font-size: 1.75rem; }
h2 { margin-top: 2rem; font-size: 1.15rem; }
.subtitle, .meta { color: var(--muted); }
nav {
  display: grid;
  gap: 0.75rem;
  margin: 2rem 0;
}
nav a, .back {
  display: block;
  padding: 0.85rem 1rem;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  color: var(--accent);
  text-decoration: none;
  font-weight: 600;
}
nav a:hover, .back:hover { border-color: var(--accent); }
ul { padding-left: 1.25rem; }
li { margin-bottom: 0.5rem; }
.footer { margin-top: 2.5rem; font-size: 0.9rem; color: var(--muted); }
a { color: var(--accent); }