:root { color-scheme: light; }
* { box-sizing: border-box; }
body {
  font-family: -apple-system, "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;
  background: #f4f5f7;
  margin: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
}
.card {
  background: #fff;
  border-radius: 8px;
  box-shadow: 0 1px 4px rgba(0,0,0,.08);
  padding: 36px;
  width: 320px;
}
.card h1 {
  font-size: 18px;
  margin: 0 0 24px;
  display: flex;
  align-items: center;
  gap: 8px;
}
label { display: block; font-size: 13px; color: #444; margin-top: 14px; }
input {
  width: 100%;
  padding: 9px 10px;
  margin-top: 4px;
  border: 1px solid #d3d6db;
  border-radius: 5px;
  font-size: 14px;
}
button {
  width: 100%;
  margin-top: 22px;
  padding: 10px;
  background: #2563eb;
  color: #fff;
  border: none;
  border-radius: 5px;
  font-size: 14px;
  cursor: pointer;
}
button:disabled { opacity: .6; cursor: default; }
.error {
  margin-top: 14px;
  background: #fdecec;
  color: #b42318;
  padding: 8px 10px;
  border-radius: 5px;
  font-size: 13px;
  display: none;
}
.signup-link { margin-top: 16px; text-align: center; font-size: 13px; }
.signup-link a { color: #2563eb; text-decoration: none; }
.signup-link a:hover { text-decoration: underline; }