#container {
  display: flex;
  flex-wrap: wrap;
  gap: 2rem;
}
#container .letter {
  display: flex;
  justify-content: center;
  align-items: center;
  width: 2rem;
  height: 2rem;
  border: 2px solid #ffffff;
  cursor: pointer;
}
#container .letter.locked {
  border: 2px solid #cc2222;
}