:root { color-scheme: dark; }
* { box-sizing: border-box; }
body {
  margin: 0; min-height: 100vh; display: flex; align-items: center; justify-content: center;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  background: #0d1117; color: #e6edf3;
}
.card {
  width: 340px; padding: 28px 26px; border-radius: 12px;
  background: #161b22; border: 1px solid #30363d; box-shadow: 0 10px 40px rgba(0,0,0,.4);
}
h1 { font-size: 18px; margin: 0 0 4px; }
p.sub { margin: 0 0 18px; color: #8b949e; font-size: 13px; }
input {
  width: 100%; padding: 10px 12px; border-radius: 8px; border: 1px solid #30363d;
  background: #0d1117; color: #e6edf3; font-size: 14px; margin-bottom: 12px;
}
button {
  width: 100%; padding: 10px 12px; border: 0; border-radius: 8px; cursor: pointer;
  background: #238636; color: #fff; font-size: 14px; font-weight: 600;
}
button:disabled { opacity: .6; cursor: default; }
.err { color: #ff7b72; font-size: 13px; min-height: 18px; margin-top: 8px; }
@media (max-width: 480px) {
  body { padding: 16px; padding-bottom: max(16px, env(safe-area-inset-bottom)); }
  .card { width: 100%; max-width: 480px; padding: 24px 18px; }
  input, button { font-size: 16px; padding: 12px; }
}