:root {
  color-scheme: light;
  font-family: Arial, "Microsoft YaHei", "Segoe UI", sans-serif;
  --bg: #f4f1ea;
  --panel: #ffffff;
  --line: #d8d2c6;
  --text: #1e2522;
  --muted: #6c746f;
  --accent: #227c70;
  --accent-dark: #175f56;
  --bad: #b42318;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
  background: var(--bg);
  color: var(--text);
}
.panel {
  width: min(420px, 100%);
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 24px;
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.08);
}
h1 { margin: 0 0 8px; font-size: 24px; }
p { margin: 0 0 16px; color: var(--muted); line-height: 1.6; }
label { display: block; margin-bottom: 8px; font-weight: 700; }
input {
  width: 100%;
  min-height: 42px;
  padding: 10px 12px;
  border-radius: 8px;
  border: 1px solid #c7c0b3;
  background: #fff;
  font-size: 16px; /* >=16 防止 iOS Safari 自动放大 */
}
button {
  width: 100%;
  min-height: 42px;
  margin-top: 14px;
  border: 1px solid var(--accent-dark);
  background: var(--accent);
  color: #fff;
  border-radius: 8px;
  cursor: pointer;
  font-size: 15px;
  font-weight: 700;
}
.error { color: var(--bad); min-height: 22px; margin-top: 10px; }
.subtitle { margin: 0 0 18px; }
button:disabled { opacity: 0.6; cursor: progress; }
.tip {
  margin-top: 14px;
  padding: 10px 12px;
  border-radius: 8px;
  background: #fbfaf7;
  border: 1px solid #e5ded2;
  color: #4f5a54;
  font-size: 14px;
  line-height: 1.55;
}
.tip code {
  font-family: Consolas, "Liberation Mono", monospace;
  background: #efe8d8;
  padding: 1px 5px;
  border-radius: 4px;
}
@media (max-width: 480px) {
  .panel { padding: 18px; }
  h1 { font-size: 20px; }
}