.start-box {
  max-width: 500px;
  float: none;
  margin: 0 auto;
  margin-top: auto;
  margin-bottom: auto;
}

body {
  background-color: gray;
}

.error {
  color: red;
  font-weight: 500;
  padding-bottom: 2rem;
  font-size: 1.5rem;
}