body {
  background-color: white;
  }

.bookstack {
  display:flex;
   flex-direction:column-reverse;

   /* fallback height */
   min-height:100vh;

   /* new small viewport height for modern browsers */
   min-height:100vh;
    align-items: center;
    justify-content: flex-start;
    gap: 5px;
}
.bookstack div {
  background-color: #f1f1f1;
  position: relative;
  padding: 20px;
  font-size: 30px;
  text-align: center;
  width: 50%;
  transition:
    width 2s,
    height 2s,
    background-color 2s,
}
.bookstack div:hover {
  background-color: #ffcccc;
  width: 200px;
  height: 200px;
}