:root {
  --fond: #f1f5f9;
  --carte: #ffffff;
  --texte: #0f172a;
  --doux: #64748b;
  --bord: #e2e8f0;
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root {
    --fond: #0b1120;
    --carte: #111827;
    --texte: #e2e8f0;
    --doux: #94a3b8;
    --bord: #1f2937;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 16px;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: var(--fond);
  color: var(--texte);
}
.carte {
  width: 100%;
  max-width: 380px;
  padding: 36px 28px;
  border-radius: 20px;
  background: var(--carte);
  border: 1px solid var(--bord);
  text-align: center;
  box-shadow: 0 10px 30px rgba(15, 23, 42, .08);
}
h1 { margin: 12px 0 6px; font-size: 1.8rem; }
.doux { margin: 0 0 24px; color: var(--doux); }
.erreur {
  margin: 0 0 18px;
  padding: 10px 12px;
  border-radius: 10px;
  background: #fee2e2;
  color: #991b1b;
  font-size: .92rem;
}
.google {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  width: 100%;
  padding: 12px 16px;
  border-radius: 12px;
  border: 1px solid var(--bord);
  background: var(--carte);
  color: var(--texte);
  font-weight: 600;
  text-decoration: none;
}
.google:hover { border-color: var(--doux); }