:root {
  color-scheme: light dark;
  --bg: #f3f4f6;
  --card: #ffffff;
  --text: #111827;
  --muted: #6b7280;
  --accent: #111827;
  --ok: #15803d;
  --fail: #b91c1c;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0f17;
    --card: #161b26;
    --text: #f3f4f6;
    --muted: #9ca3af;
    --accent: #f3f4f6;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 16px;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.5 system-ui, -apple-system, "Segoe UI", sans-serif;
}
.card {
  width: 100%;
  max-width: 420px;
  background: var(--card);
  border-radius: 16px;
  padding: 28px 24px;
  text-align: center;
  box-shadow: 0 1px 3px rgb(0 0 0 / 0.1);
}
h1 { font-size: 1.4rem; margin: 0 0 12px; }
.name { font-size: 1.25rem; font-weight: 600; margin: 8px 0 0; }
.muted { color: var(--muted); margin: 4px 0; }
.small { font-size: 0.85rem; }
.error { color: var(--fail); }
/* QR stays black-on-white in dark mode so scanners can read it */
.qr {
  background: #fff;
  border-radius: 12px;
  padding: 8px;
  margin: 20px auto 8px;
  max-width: 320px;
  transition: opacity 0.2s;
}
.qr svg { display: block; width: 100%; height: auto; }
.qr.stale { opacity: 0.25; }
.countdown { font-variant-numeric: tabular-nums; font-weight: 500; margin: 4px 0 12px; }
form { display: grid; gap: 10px; margin-top: 20px; text-align: left; }
input, button { font: inherit; padding: 10px 12px; border-radius: 8px; }
input { border: 1px solid var(--muted); background: transparent; color: var(--text); }
button { border: 0; background: var(--accent); color: var(--card); font-weight: 600; cursor: pointer; }
.status {
  width: 88px; height: 88px; margin: 0 auto 16px;
  border-radius: 50%;
  display: grid; place-items: center;
  font-size: 48px; color: #fff;
}
.status.ok { background: var(--ok); }
.status.fail { background: var(--fail); }
a { color: inherit; }