:root {
  --bg: #f5f5f4;
  --card: #fff;
  --ink: #1c1c1c;
  --muted: #6b6b6b;
  --line: #e3e3e1;
  --accent: #2f6fd8;
  --accent-ink: #fff;
  --error: #c62828;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #161616;
    --card: #202020;
    --ink: #f0f0f0;
    --muted: #a0a0a0;
    --line: #343434;
    --accent: #4d8bf0;
    --error: #ff6b6b;
    color-scheme: dark;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100dvh;
  display: grid;
  place-items: center;
  padding: 16px;
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}
main { width: 100%; max-width: 380px; }
.card {
  display: grid;
  gap: 14px;
  padding: 28px 24px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.06);
}
h1 { margin: 0; font-size: 22px; font-weight: 600; }
.hint { margin: -8px 0 6px; color: var(--muted); font-size: 14px; }
label { display: grid; gap: 6px; color: var(--muted); font-size: 14px; }
input {
  padding: 10px 12px;
  color: var(--ink);
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 10px;
  outline: none;
  font: inherit;
}
input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(47, 111, 216, 0.2); }
#error { margin: 0; min-height: 1.2em; color: var(--error); font-size: 14px; }
button {
  padding: 11px;
  color: var(--accent-ink);
  background: var(--accent);
  border: 0;
  border-radius: 10px;
  cursor: pointer;
  font: inherit;
  font-weight: 600;
}
button:disabled { opacity: 0.6; cursor: default; }