:root {
  color-scheme: light dark;
  --bg: #f2f3f5;
  --fg: #1a1a1a;
  --card-bg: #ffffff;
  --border: #e2e4e8;
  --accent: #25d366;
  --accent-strong: #1da851;
  --accent-fg: #063d1f;
  --error: #c0392b;
  --shadow: 0 1px 2px rgba(16, 24, 40, 0.06), 0 1px 3px rgba(16, 24, 40, 0.08);
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #101114; --fg: #e8e9ec; --card-bg: #1b1c20; --border: #2b2d33; }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, system-ui, "Segoe UI", sans-serif;
}
form {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 2rem;
  width: 100%;
  max-width: 320px;
  box-shadow: var(--shadow);
}
h1 { font-size: 1.1rem; margin: 0 0 1.25rem; }
label { display: block; font-size: 0.85rem; margin-bottom: 1rem; }
input {
  display: block;
  width: 100%;
  margin-top: 0.35rem;
  padding: 0.55rem 0.65rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  color: var(--fg);
  font-size: 0.9rem;
}
button {
  width: 100%;
  background: var(--accent);
  color: var(--accent-fg);
  border: none;
  border-radius: 8px;
  padding: 0.6rem;
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
}
button:hover { background: var(--accent-strong); }
.error { color: var(--error); font-size: 0.85rem; margin: 0.75rem 0 0; min-height: 1em; }
p { font-size: 0.85rem; line-height: 1.45; margin: 0 0 1.25rem; }
.hint { opacity: 0.7; font-size: 0.8rem; margin: -0.5rem 0 1rem; }