* { box-sizing: border-box; }
body {
  margin: 0; height: 100vh;
  display: flex; align-items: center; justify-content: center;
  font-family: 'Pretendard', -apple-system, 'Apple SD Gothic Neo', 'Inter', system-ui, sans-serif;
  background: #fafbfc;
  color: #1f2328;
}
.card {
  background: #fff;
  padding: 40px 36px;
  border-radius: 14px;
  min-width: 340px;
  display: flex; flex-direction: column; gap: 14px;
  border: 1px solid #ebecf0;
  box-shadow: 0 12px 32px rgba(31, 35, 40, 0.06);
}
h1 {
  margin: 0 0 8px;
  font-size: 18px; font-weight: 700;
  text-align: center; color: #1f2328;
}
input {
  padding: 12px 14px;
  border: 1px solid #d8d9dd;
  border-radius: 8px;
  font-size: 18px;
  text-align: center;
  letter-spacing: 6px;
  font-family: inherit;
}
input:focus {
  outline: none;
  border-color: #0066ff;
  box-shadow: 0 0 0 3px rgba(0, 102, 255, 0.12);
}
button {
  padding: 11px;
  border: 0;
  border-radius: 8px;
  background: #0066ff;
  color: #fff;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  font-family: inherit;
}
button:hover { background: #0052cc; }
.err { color: #d1242f; font-size: 13px; text-align: center; min-height: 18px; }