@media (max-width: 768px) {
  body { padding-top: 5vh; }
  main { width: 90%; padding: 35px 20px; }
  h1 { font-size: 1.8rem; margin-bottom: 25px; }
  input, button { width: 100%; font-size: 1rem; }
  #number { font-size: 2.8rem; }
  #rewardModalContent { width: 90%; padding: 20px; }
}