body {
  margin: 0;
  padding: 2rem;
  display: flex;
  justify-content: center;
}

main {
  text-align: center;
  max-width: 500px;
}

main img {
  max-width: 100%;
  height: auto;
}

#phone-message { margin-top: 0.5rem; }
.success { color: green; }
.error { color: red; }