#puzzle-container {
  display: grid;
  grid-template-columns: repeat(3, 100px);
  grid-template-rows: repeat(3, 100px);
  gap: 5px;
  width: max-content;
  margin: 20px auto;
}

/* .tile {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  background-color: #6c6b92;
  color: white;
  cursor: pointer;
  user-select: none;
} */

.tile {
  width: 100px;
  height: 100px;
  background-image: url("../img/train2.png");
  background-size: 300px 300px;
  /* total image size */
  border: 1px solid #fff;
  box-sizing: border-box;
}

.empty {
  background: #ccc;
  cursor: default;
}

@media screen and (max-width: 767px) {
  #puzzle-container {
    margin: 0 -15px;
  }
}