:root {
  color-scheme: dark;
  --bg: #0f1115;
  --surface: #171a21;
  --line: #262b35;
  --fg: #e6e8eb;
  --dim: #7f8794;
  --label: #9aa3b0;
  --accent: #3d7eff;
  --bad: #ff6b6b;
  --input-bg: #0f1218;
  --input-line: #2c3340;
}

@media (prefers-color-scheme: light) {
  :root {
    color-scheme: light;
    --bg: #f4f6fa;
    --surface: #ffffff;
    --line: #e2e7ef;
    --fg: #141a23;
    --dim: #66707f;
    --label: #5a6577;
    --accent: #2f6fe0;
    --bad: #cf3346;
    --input-bg: #f7f9fc;
    --input-line: #cbd3e0;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", "PingFang SC", sans-serif;
  background: var(--bg);
  color: var(--fg);
}

main {
  width: 100%;
  max-width: 320px;
  padding: 28px 26px 24px;
  border-radius: 14px;
  background: var(--surface);
  border: 1px solid var(--line);
  box-shadow: 0 18px 50px rgba(0, 0, 0, .35);
}

h1 {
  margin: 0 0 4px;
  font-size: 17px;
  font-weight: 600;
  letter-spacing: .2px;
}

p.sub {
  margin: 0 0 20px;
  font-size: 12px;
  color: var(--dim);
}

label {
  display: block;
  font-size: 12px;
  color: var(--label);
  margin-bottom: 6px;
}

input {
  width: 100%;
  padding: 10px 12px;
  font-size: 14px;
  font-family: inherit;
  border-radius: 8px;
  border: 1px solid var(--input-line);
  background: var(--input-bg);
  color: var(--fg);
}
input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(61, 126, 255, .18);
}

button {
  width: 100%;
  margin-top: 16px;
  padding: 10px;
  font-size: 14px;
  font-family: inherit;
  font-weight: 600;
  border: 0;
  border-radius: 8px;
  background: var(--accent);
  color: #fff;
  cursor: pointer;
}
button:disabled { opacity: .6; cursor: default; }

p.msg {
  margin: 12px 0 0;
  font-size: 12px;
  min-height: 16px;
  color: var(--bad);
}
p.msg:empty { min-height: 0; }