:root {
  color-scheme: light dark;
  --bg: #f5f7fb;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --accent: #2563eb;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b1220;
    --card: #111827;
    --text: #e5e7eb;
    --muted: #94a3b8;
  }
}

* { 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;
}

a { color: var(--accent); }

header, main, footer {
  max-width: 720px;
  margin: 0 auto;
  padding: 1.25rem;
}

header {
  padding-top: 2rem;
}

.brand {
  font-weight: 700;
  font-size: 1.25rem;
  letter-spacing: -0.02em;
}

.card {
  background: var(--card);
  border-radius: 12px;
  padding: 1.5rem;
  box-shadow: 0 1px 3px rgba(15, 23, 42, 0.08);
}

.muted { color: var(--muted); font-size: 0.95rem; }

h1 { font-size: 1.75rem; margin-top: 0; }
h2 { font-size: 1.15rem; margin-top: 1.75rem; }
ul { padding-left: 1.25rem; }

footer { padding-bottom: 2rem; font-size: 0.9rem; color: var(--muted); }