.tile {
  --length: 80px;
  width: var(--length);
  height: var(--length);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background-color: transparent;
  border: 2px solid black;
  border-radius: 8px;
  margin: 2px 0;
  outline: 0;
}

.tile:hover {
  background-color: #e4e4e4;
  cursor: pointer;
}

#restart-button {
  display: none;
}