.book-container{
  --book-width: 176px;
  --book-height: 250px;
  --book-thickness: 13px;
  padding-top: calc(0.3 * var(--book-width));
  padding-bottom: calc(0.3 * var(--book-width));
  padding-left: calc(0.3 * var(--book-width));
  padding-right: calc(0.3 * var(--book-width));
  display: flex;
  align-items: center;
  justify-content: center;
  transform-style: preserve-3d;
  perspective: 1000px;
}

.book {
  --book-initial-x-rotation: 10deg;
  --book-initial-y-rotation: 30deg;
  --book-initial-z-rotation: 0deg;
  --book-pages-color: white;
  --book-cover: "";
}

.type1{
  --book-initial-x-rotation: 10deg;
  --book-initial-y-rotation: 10deg;
  --book-initial-z-rotation: 0deg;
}
.type2{
  --book-initial-x-rotation: -10deg;
  --book-initial-y-rotation: -10deg;
  --book-initial-z-rotation: 2deg;
}

.book{
    position: relative;
    width: var(--book-width);
    height: var(--book-height);
    transform: rotateX(var(--book-initial-x-rotation))
               rotateY(var(--book-initial-y-rotation))
               rotateZ(var(--book-initial-z-rotation));
    transform-style: preserve-3d;
}

.book > ._side{
    border: 1px solid darkgrey;
}

.book > ._side:nth-of-type(1){
    width: var(--book-width);
    height: var(--book-height);
    position: absolute;
    transform: translateZ(calc(var(--book-thickness) * 0.5));

    background: var(--book-cover) no-repeat center right scroll;
    background-size: cover;
}

.book > ._side:nth-of-type(2){
    width: var(--book-width);
    height: var(--book-height);
    position: absolute;

    background-color: white;
    background: var(--book-cover) no-repeat center left scroll;
    background-size: cover;
    transform: rotateY(180deg) translateZ(calc(var(--book-thickness) * 0.5));
}

.book > ._side:nth-of-type(3){
    background-color: var(--book-pages-color);
    width: var(--book-thickness);
    height: var(--book-height);
    position: absolute;
    transform:
        translateX(var(--book-width))
        rotateY(90deg)
        translateZ(calc(var(--book-thickness) * -0.5));
}

.book > ._side:nth-of-type(4){
    background-color: var(--book-pages-color);
    height: var(--book-thickness);
    width: var(--book-width);
    position: absolute;
    transform:
        rotateX(90deg)
        translateZ(calc(var(--book-thickness) * 0.5));
}

.book > ._side:nth-of-type(5){
    background-color: var(--book-pages-color);
    height: var(--book-thickness);
    width: var(--book-width);
    position: absolute;
    transform:
        rotateX(270deg)
        translateZ(calc(var(--book-height) + var(--book-thickness) * -0.5));
}

.book > ._side:nth-of-type(6){
    background: var(--book-cover) no-repeat center center scroll;
    width: var(--book-thickness);
    height: var(--book-height);
    background-size: cover;
    position: absolute;
    transform:
        rotateY(270deg)
        translateZ(calc(var(--book-thickness) * 0.5));
}


/*ANIMATION*/
@keyframes rotate {
  from {
    transform: rotateX(var(--book-initial-x-rotation))
               rotateY(var(--book-initial-y-rotation))
               rotateZ(var(--book-initial-z-rotation));
  }

  to {
    transform: rotateX(var(--book-initial-x-rotation))
               rotateY(calc(var(--book-initial-y-rotation) + 360deg))
               rotateZ(var(--book-initial-z-rotation));
  }
}

.book-container:hover >.book{
  animation: rotate 15s infinite linear;
  transition: none;
}


.flex-around-wrap{
  display: flex;
  justify-content: space-around;
  flex-wrap: wrap;
}