:root {
  --bg: #f4f6fa;
  --surface: #ffffff;
  --text: #16202e;
  --muted: #5b6676;
  --brand: #1f4e8c;
  --line: #e2e7ef;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f141b;
    --surface: #171e28;
    --text: #e8edf4;
    --muted: #9aa6b6;
    --brand: #7fa6e3;
    --line: #273142;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

main {
  max-width: 760px;
  margin: 0 auto;
  padding: 32px 16px 64px;
}

header { margin-bottom: 24px; }
header a.home { color: var(--brand); font-weight: 800; text-decoration: none; font-size: 18px; }

h1 { font-size: 30px; line-height: 1.2; margin: 12px 0 4px; }
h2 { font-size: 20px; margin: 32px 0 8px; }
h3 { font-size: 16px; margin: 20px 0 4px; }
p, ul { margin: 0 0 12px; }
ul { padding-left: 20px; }
a { color: var(--brand); }
.muted { color: var(--muted); font-size: 14px; }

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 20px;
  margin: 16px 0;
}

nav.links { display: flex; flex-wrap: wrap; gap: 8px 20px; margin-top: 40px; padding-top: 16px; border-top: 1px solid var(--line); font-size: 14px; }