* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  font-family: Arial, sans-serif;
  background: #f6f7f9;
  color: #111827;
}
.auth-box {
  width: min(360px, calc(100vw - 28px));
  padding: 18px;
  border: 1px solid #e5e7eb;
  border-radius: 12px;
  background: #fff;
}
h1 { margin: 0 0 6px; font-size: 22px; }
.muted { color: #6b7280; font-size: 13px; }
form { display: grid; gap: 9px; margin-top: 14px; }
input, button {
  width: 100%;
  border-radius: 8px;
  padding: 10px 11px;
  font: inherit;
}
input { border: 1px solid #e5e7eb; }
button {
  border: 0;
  color: #fff;
  background: #1683d8;
  cursor: pointer;
  font-weight: 700;
}
.message { min-height: 18px; color: #dc2626; font-size: 13px; }
a { color: #1683d8; }