:root {
  --bg: #eef2f7;
  --surface: #fff;
  --ink: #172033;
  --muted: #697386;
  --line: #dbe2ec;
  --primary: #2563eb;
  --nav: #0f172a;
  --danger: #dc2626;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  background: var(--bg);
  font-family: "Microsoft YaHei", sans-serif;
}
button, input { font: inherit; }
.shell {
  display: grid;
  grid-template-columns: minmax(360px, .9fr) minmax(440px, 1.1fr);
  min-height: 100vh;
}
.intro {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  min-height: 100vh;
  padding: clamp(32px, 6vw, 82px);
  color: #fff;
  background: var(--nav);
}
.brand {
  color: #fff;
  font-size: 20px;
  font-weight: 800;
  text-decoration: none;
}
.intro-copy { max-width: 520px; }
.intro-copy h1 {
  max-width: 620px;
  margin: 0;
  font-size: clamp(38px, 5vw, 68px);
  line-height: 1.08;
}
.intro-copy p {
  max-width: 500px;
  margin: 20px 0 0;
  color: #b7c2d5;
  font-size: 16px;
  line-height: 1.8;
}
.intro-links { display: flex; flex-wrap: wrap; gap: 12px; }
.intro-links a {
  color: #cbd5e1;
  font-size: 13px;
  text-decoration: none;
}
.form-side {
  display: grid;
  place-items: center;
  min-width: 0;
  padding: 32px;
}
.login-card {
  width: min(420px, 100%);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 30px;
  background: var(--surface);
  box-shadow: 0 20px 60px rgba(25, 39, 67, .1);
}
.login-card h2 { margin: 0; font-size: 25px; }
.login-card > p { margin: 7px 0 24px; color: var(--muted); font-size: 13px; }
.field { display: grid; gap: 7px; margin-bottom: 15px; }
.field label { color: #475467; font-size: 13px; font-weight: 700; }
.field input {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 11px 12px;
  color: var(--ink);
  background: #fff;
  outline: none;
}
.field input:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(37, 99, 235, .1); }
.error { min-height: 22px; color: var(--danger); font-size: 13px; }
.submit {
  width: 100%;
  min-height: 44px;
  border: 1px solid var(--primary);
  border-radius: 7px;
  color: #fff;
  background: var(--primary);
  cursor: pointer;
  font-weight: 800;
}
.submit:disabled { opacity: .55; cursor: wait; }
.switch {
  margin-top: 18px;
  color: var(--muted);
  font-size: 13px;
  text-align: center;
}
.switch a { color: var(--primary); font-weight: 700; text-decoration: none; }
@media (max-width: 760px) {
  .shell { display: block; }
  .intro {
    min-height: auto;
    padding: 28px 22px 38px;
  }
  .intro-copy { margin-top: 58px; }
  .intro-copy h1 { font-size: 36px; }
  .intro-copy p { font-size: 14px; }
  .intro-links { display: none; }
  .form-side { padding: 18px 14px 36px; }
  .login-card { margin-top: -22px; padding: 24px 20px; }
}