.book-container {
  display: flex;
  align-items: center;
  justify-content: center;
  perspective: 600px;
}

@keyframes initAnimation {
  0% { transform: rotateY(-45deg); }
  100% { transform: rotateY(-5deg); }
}

.book {
  width: 25vw;
  height: 37.5vw; /* Maintaining the aspect ratio */
  position: relative;
  transform-style: preserve-3d;
  transform: rotateY(-5deg);
  transition: 1s ease;
  animation: 1s ease 0s 1 initAnimation;
}

.book-container:hover .book, 
.book-container:focus .book {transform: rotateY(-55deg);}

.book > :first-child {
  position: absolute;
  top: 0;
  left: 0;
  background-color: #990033;
  width: 100%;
  height: 100%;
  transform: translateZ(10px);
  border-radius: 0 5px 5px 0;
  box-shadow: 5px 5px 20px #666;
}

.book::before {
  position: absolute;
  content: ' ';
  background-color: blue;
  left: 95%;
  top: 5px;
  width: 18px;
  height:97%;
  transform: rotateY(90deg);
  background: linear-gradient(90deg, 
    #fff 0%,
    #f9f9f9 5%,
    #fff 10%,
    #f9f9f9 15%,
    #fff 20%,
    #f9f9f9 25%,
    #fff 30%,
    #f9f9f9 35%,
    #fff 40%,
    #f9f9f9 45%,
    #fff 50%,
    #f9f9f9 55%,
    #fff 60%,
    #f9f9f9 65%,
    #fff 70%,
    #f9f9f9 75%,
    #fff 80%,
    #f9f9f9 85%,
    #fff 90%,
    #f9f9f9 95%,
    #fff 100%
    );
}

.book::after {
  position: absolute;
  top: 0;
  left: 0;
  content: ' ';
  width: 100%;
  height: 100%; 
  transform: translateZ(-10px);
  background-color: #990033;
  border-radius: 0 5px 5px 0;
  box-shadow: -10px 0 50px 10px #666;
}

.book {
  max-width: 250px;
  max-height: 375px;
}