:root{--deep:#0e2440;--blue:#2384dd;--line:#dbe7f4;--bg:#eef4fa;--txt:#1f2a37;--faint:#6b7f97}
*{box-sizing:border-box}
body{margin:0;min-height:100vh;display:flex;align-items:center;justify-content:center;
  background:radial-gradient(1200px 600px at 20% -10%,#dcebf9 0%,var(--bg) 60%);color:var(--txt);
  font-family:"Microsoft YaHei","PingFang SC",system-ui,-apple-system,sans-serif}
.card{width:min(92vw,380px);background:#fff;border:1px solid var(--line);border-top:4px solid var(--blue);
  padding:30px 28px 22px;box-shadow:0 18px 45px rgba(14,36,64,.10)}
.brand{display:flex;align-items:center;gap:9px;font-size:19px;font-weight:700;color:var(--deep);letter-spacing:.5px}
.dot{width:11px;height:11px;border-radius:50%;background:var(--blue);box-shadow:0 0 0 4px rgba(35,132,221,.16)}
.sub{margin:8px 0 20px;font-size:12px;color:var(--faint);letter-spacing:.3px}
label{display:block;font-size:13px;color:var(--deep);margin-bottom:14px;font-weight:600}
input{display:block;width:100%;margin-top:6px;padding:11px 12px;font-size:15px;color:var(--txt);
  border:1px solid var(--line);background:#fbfdff;outline:none;border-radius:3px}
input:focus{border-color:var(--blue);box-shadow:0 0 0 3px rgba(35,132,221,.14)}
button{width:100%;margin-top:6px;padding:12px;font-size:16px;letter-spacing:4px;font-weight:700;color:#fff;
  background:linear-gradient(180deg,#2f92e6,#1d74c4);border:0;border-radius:3px;cursor:pointer}
button:hover{filter:brightness(1.06)}
button:active{transform:translateY(1px)}
.err{margin:0 0 16px;padding:9px 11px;font-size:12.5px;color:#8f2b20;background:#fdf1ef;border-left:3px solid #c0392b}
.tip{margin:18px 0 0;font-size:11.5px;color:var(--faint);line-height:1.6}