* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 20px;
  color: #1e293b;
  background: linear-gradient(135deg, #4f46e5, #7c3aed);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}
.login-card {
  width: min(380px, 100%);
  padding: 36px;
  border-radius: 16px;
  background: #fff;
  box-shadow: 0 20px 60px rgba(15, 23, 42, .3);
}
h1 { margin: 0 0 6px; font-size: 24px; }
p { margin: 0 0 24px; color: #64748b; }
label { display: block; margin-bottom: 7px; font-size: 13px; font-weight: 600; }
input, button {
  width: 100%;
  min-height: 44px;
  border-radius: 9px;
  font: inherit;
}
input {
  padding: 10px 12px;
  border: 1.5px solid #cbd5e1;
}
input:focus {
  outline: none;
  border-color: #4f46e5;
  box-shadow: 0 0 0 3px rgba(79, 70, 229, .12);
}
button {
  margin-top: 14px;
  border: 0;
  color: #fff;
  background: #4f46e5;
  cursor: pointer;
  font-weight: 650;
}
button:disabled { opacity: .65; cursor: wait; }
.error { min-height: 20px; margin-top: 10px; color: #dc2626; font-size: 13px; }