.preloading{
    width: 150px;
    height: 130px;
    position: absolute;
    top:0;
    left: 0;
    right: 0;
    bottom: 0;
    transform: translateY(-50%);
    margin: auto;
    text-align: center;
  }
.preloading .book-box{
    width: 150px;
    height: 100px;
    border: 6px solid var(--primary-color);
    border-radius: 5px;
    margin-bottom: 20px;
  }
.preloading .book{
      width: 100%;
      height: 100%;
      position: relative;
      perspective: 850px;
  }
.preloading .page{
      position: absolute;
      width: 50%;
      height: 100%;
      box-sizing: border-box;
      border: 1px solid #ddd;
      top: 0;
      padding: 6px;
      display: flex;
      flex-direction: column;
      justify-content: space-around;
      background-color: #fff;
  }
.preloading .page div{
      height: 3px;
      background-color: #ddd;
  }
.preloading .page1 div:nth-of-type(1),
.preloading .page1 div:nth-of-type(10),
.preloading .page3  div:nth-of-type(10),
.preloading .page3  div:nth-of-type(1),
.preloading .page2 div:nth-of-type(4),
.preloading .page4 div:nth-of-type(4){
      width: 50%;
  }
.preloading  .page1 div:nth-of-type(5),
.preloading  .page3 div:nth-of-type(5),
.preloading  .page2 div:nth-of-type(7),
.preloading  .page4 div:nth-of-type(7){
      width: 80%;
  }
.preloading  .page1 div:nth-of-type(6),
.preloading  .page3  div:nth-of-type(6){
      width: 70%;
  }
.preloading  .page1  div:nth-of-type(9),
.preloading  .page3  div:nth-of-type(9){
      width: 90%;
  }
.preloading  .page2 div:nth-of-type(8),
.preloading  .page4 div:nth-of-type(8){
      width: 40%;
  }
.preloading  .page1, .preloading .page3{
      left: 0;
      box-shadow: inset -5px 0px 15px rgba(0, 0, 0, 0.1);
  }
.preloading  .page2, .preloading .page3, .preloading .page4{
      right: 0;
      transform: rotateY(0deg);
  }
.preloading  .page2{
      transform: rotateY(0deg);
      transform-origin: left;
      animation: turn .7s linear forwards infinite;
      z-index: 1;
  }
.preloading  .page3{
      transform: rotateY(90deg);
      transform-origin: right;
      animation: turn2 .7s linear forwards infinite;
      z-index: 1;
  }
.preloading  .page3 div{
      width: 100%;
  }
  @keyframes turn {
      0% {
          transform: rotateY(0deg);
      }
      100% {
          transform: rotateY(-90deg);
      }
  }
  @keyframes turn2 {
      0% {
          transform: rotateY(90deg);
      }
      100% {
          transform: rotateY(0deg);
      }
  }