:root {
  --bg: #f5f6f8;
  --card: #ffffff;
  --text: #1c2430;
  --muted: #5b6574;
  --border: #dde1e7;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1419;
    --card: #182029;
    --text: #e6eaf0;
    --muted: #9aa5b4;
    --border: #2a3440;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16px;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}
.card {
  width: 100%;
  max-width: 420px;
  padding: 24px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
}
h1 { margin: 0 0 8px; font-size: 18px; font-weight: 600; }
p { margin: 0; color: var(--muted); }