.book {
    position: relative;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
    height: 12.5rem;
    perspective: 70rem;
    text-align: justify;
}

@media (max-width: 850px) {
    .book {
        width: 18.5rem;
    }
}

@media (min-width: 851px) {
    .book {
        margin-left: 40px;
    }
}

.cover {
    transform: rotateY(0deg);
    width: 9.25rem;
    height: 12.5rem;
}
.page {
    top: 0.25rem;
    left: 0.25rem;
    background-color: #e9e6c4;
    transform: rotateY(0deg);
    width: 9rem;
    height: 12rem;
    font-size: 28px;
    color: #777;
    font-family: sans-serif;
    box-shadow: inset 3px 0px 20px rgba(0, 0, 0, 0.2),
                    0px 0px 15px rgba(0, 0, 0, 0.1);
}
.page::before, .page::after {
    display: block;
    border-top: 1px dashed rgba(0, 0, 0, 0.3);
    content: "";
    padding-bottom: 1rem;
}
.cover, .page {
    position: absolute;
    padding: 1rem;
    transform-origin: 100% 0;
    border-radius: 5px 0 0 5px;
    box-sizing: border-box;
}
.cover.turn {
    animation: bookCover 3s forwards;
}
.page.turn {
    animation: bookOpen 3s forwards;
}
.page:nth-of-type(1) {
    animation-delay: 0.05s;
}
.page:nth-of-type(2) {
    animation-delay: 0.33s;
}
.page:nth-of-type(3) {
    animation-delay: 0.66s;
}
.page:nth-of-type(4) {
    animation: bookOpen150deg 3s forwards;
    animation-delay: 0.99s;
}
.page:nth-of-type(5) {
    animation: bookOpen30deg 3s forwards;
    animation-delay: 1.2s;
}
.page:nth-of-type(6) {
    animation: bookOpen55deg 3s forwards;
    animation-delay: 1.25s;
}
@keyframes bookOpen {
    30% { z-index: 999 }
    100% { transform: rotateY(180deg);
    z-index: 999;}
}
@keyframes bookCover {
    30% { z-index: 999 }
    100% { transform: rotateY(180deg);
    z-index: 1;}
}
@keyframes bookOpen150deg {
    30% { z-index: 999 }
    100% { transform: rotateY(150deg);
    z-index: 999;}
}
@keyframes bookOpen55deg {
    30% { z-index: 999 }
    100% { transform: rotateY(55deg);
    z-index: 999;}
}
@keyframes bookOpen30deg {
    50% { z-index: 999 }
    100% { transform: rotateY(30deg);
    z-index: 999;}
}