:root {
  color-scheme: light dark;
  --bg: #f5f5f7;
  --card: #ffffff;
  --text: #1d1d1f;
  --muted: #6e6e73;
  --border: #d2d2d7;
  --accent: #0071e3;
  --accent-text: #ffffff;
  --error: #d70015;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1c1c1e;
    --card: #2c2c2e;
    --text: #f5f5f7;
    --muted: #98989d;
    --border: #48484a;
    --accent: #0a84ff;
    --error: #ff453a;
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
body { margin: 0; min-height: 100vh; background: var(--bg); color: var(--text); }

.center { min-height: 100vh; display: grid; place-items: center; padding: 16px; }
.card {
  width: 100%; max-width: 340px; display: flex; flex-direction: column; gap: 12px;
  align-items: stretch; text-align: center; background: var(--card);
  border: 1px solid var(--border); border-radius: 16px; padding: 32px 24px;
}
.logo { width: 72px; height: 72px; align-self: center; }
h1 { font-size: 22px; margin: 4px 0; }
.subtitle { color: var(--muted); margin: 0 0 4px; line-height: 1.4; }

input {
  font: inherit; font-size: 16px; padding: 10px 12px; border-radius: 8px;
  border: 1px solid var(--border); background: var(--bg); color: var(--text);
}
input:focus { outline: 2px solid var(--accent); outline-offset: -1px; }
.code { font-family: ui-monospace, Menlo, monospace; font-size: 24px; letter-spacing: 6px; text-align: center; }

button {
  font: inherit; font-size: 16px; padding: 10px 12px; border-radius: 8px; border: 0;
  background: var(--accent); color: var(--accent-text); cursor: pointer;
}
button:disabled { opacity: .5; cursor: default; }
button.link { background: none; color: var(--accent); padding: 4px; }
button.secondary { background: none; color: var(--text); border: 1px solid var(--border); font-size: 14px; padding: 6px 12px; }

.error { color: var(--error); margin: 0; min-height: 1.2em; font-size: 14px; }

header {
  display: flex; align-items: center; gap: 10px; padding: 10px 16px;
  border-bottom: 1px solid var(--border); background: var(--card);
}
.header-logo { width: 28px; height: 28px; }
.title { font-weight: 600; }
.spacer { flex: 1; }
#who { color: var(--muted); font-size: 14px; }
.content { min-height: calc(100vh - 53px); }

.spinner {
  width: 24px; height: 24px; border-radius: 50%;
  border: 3px solid var(--border); border-top-color: var(--muted);
  animation: spin .8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }