:root {
  --bg: #0e1116;
  --bg-2: #161b22;
  --bg-3: #1c232d;
  --border: #2a323d;
  --text: #e6edf3;
  --muted: #8b949e;
  --accent: #3b82f6;
  --accent-2: #1d4ed8;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  min-height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 14px;
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  min-height: 100vh;
}

.card {
  width: 100%;
  max-width: 360px;
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 28px 26px 24px;
}

h1 {
  margin: 0;
  font-size: 22px;
  letter-spacing: .3px;
}

.sub {
  margin: 4px 0 22px;
  color: var(--muted);
  font-size: 13px;
}

label {
  display: block;
  margin: 14px 0 6px;
  font-size: 12px;
  font-weight: 600;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: .5px;
}

input {
  width: 100%;
  padding: 10px 12px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--bg-3);
  color: var(--text);
  font-size: 15px;
  outline: none;
}
input:focus { border-color: var(--accent); }

#code {
  letter-spacing: 6px;
  font-variant-numeric: tabular-nums;
}

button {
  width: 100%;
  margin-top: 22px;
  padding: 11px 12px;
  border: none;
  border-radius: 8px;
  background: var(--accent-2);
  color: #fff;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
}
button:hover:not(:disabled) { background: var(--accent); }
button:disabled { opacity: .55; cursor: default; }

.error {
  margin-top: 16px;
  padding: 10px 12px;
  border-radius: 8px;
  background: #3f1d1d;
  border: 1px solid #7f1d1d;
  color: #fca5a5;
  font-size: 13px;
}