:root {
  --brand: #7c3aed;
  --brand2: #a855f7;
  --ink: #1f2430;
  --muted: #6b7280;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
  font-family: -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  min-height: 100vh; display: flex; align-items: center; justify-content: center;
  background:
    radial-gradient(900px 500px at 10% -10%, rgba(124,58,237,.18), transparent 60%),
    radial-gradient(900px 500px at 110% 110%, rgba(168,85,247,.16), transparent 60%),
    #f6f5fb;
  padding: 20px;
}
.auth-card {
  width: 100%; max-width: 400px; background: #fff;
  border-radius: 20px; padding: 38px 34px;
  box-shadow: 0 20px 60px rgba(90,60,200,.14);
}
.brand { text-align: center; margin-bottom: 26px; }
.brand .badge {
  width: 56px; height: 56px; border-radius: 16px; margin: 0 auto 12px;
  background: linear-gradient(135deg, var(--brand), var(--brand2));
  color: #fff; display: grid; place-items: center; font-size: 30px; font-weight: 700;
}
.brand h1 { font-size: 22px; }
.brand p { color: var(--muted); font-size: 13px; margin-top: 6px; }
.field { margin-bottom: 16px; }
.field label { display: block; font-size: 13px; color: #555; margin-bottom: 7px; }
.field input {
  width: 100%; padding: 12px 14px; border: 1px solid #e2e2ea; border-radius: 11px;
  font-size: 15px; transition: border-color .15s, box-shadow .15s;
}
.field input:focus { outline: none; border-color: var(--brand);
  box-shadow: 0 0 0 3px rgba(124,58,237,.12); }
.btn {
  width: 100%; padding: 13px; border: 0; border-radius: 11px; cursor: pointer;
  background: linear-gradient(90deg, var(--brand), var(--brand2));
  color: #fff; font-size: 15px; font-weight: 600; margin-top: 6px;
  box-shadow: 0 8px 20px rgba(124,58,237,.28);
}
.btn:hover { transform: translateY(-1px); }
.alt { text-align: center; margin-top: 20px; font-size: 14px; color: var(--muted); }
.alt a { color: var(--brand); font-weight: 600; }
.back { text-align: center; margin-top: 16px; font-size: 13px; }
.back a { color: #9aa0ac; }
.err {
  background: #fef2f2; color: #dc2626; border-radius: 10px;
  padding: 10px 14px; font-size: 13px; margin-bottom: 16px;
}
.hint { font-size: 12px; color: #9aa0ac; margin-top: 6px; }