:root {
  color: #30343b;
  background: #fff;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}

* { box-sizing: border-box; }

body {
  min-width: 320px;
  min-height: 100vh;
  margin: 0;
  background: #fff;
}

.login-shell {
  display: grid;
  min-height: 100vh;
  place-items: center;
  padding: 48px 24px;
}

.login-card {
  width: min(100%, 420px);
  display: grid;
  gap: 20px;
}

.login-card h1 {
  margin: 0 0 4px;
  color: #1f2329;
  font-size: 28px;
  line-height: 1.25;
  letter-spacing: -.02em;
  text-align: center;
}

.login-intro {
  margin: 0 0 12px;
  color: #6b7280;
  text-align: center;
}

.field {
  display: grid;
  gap: 8px;
  color: #30343b;
  font-size: 15px;
  font-weight: 600;
}

.field input {
  width: 100%;
  height: 48px;
  padding: 0 13px;
  border: 1px solid #a8adb4;
  border-radius: 6px;
  color: #1f2329;
  font: inherit;
  font-weight: 400;
  outline: none;
}

.field input:focus {
  border-color: #1f75cb;
  box-shadow: 0 0 0 3px rgba(31, 117, 203, .16);
}

.login-submit {
  width: 100%;
  height: 48px;
  border: 0;
  border-radius: 6px;
  background: #1f75cb;
  color: #fff;
  font: inherit;
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
}

.login-submit:hover { background: #155fa8; }
.login-error { min-height: 1.4em; margin: -4px 0 0; color: #c33; }

@media (max-width: 520px) {
  .login-shell { padding: 32px 20px; }
  .login-card h1 { font-size: 24px; }
}