.book-btn {
    display: inline-block;
    text-transform: uppercase;
    text-decoration: none;
    border: 2px solid black;
    margin-top: 100px;
    font-size: 0.7em;
    font-weight: 700;
    padding: 0.1em 0.4em;
    margin-left: 40px;
    text-align: center;
    -webkit-transition: color 0.3s, border-color 0.3s;
    -moz-transition: color 0.3s, border-color 0.3s;
    transition: color 0.3s, border-color 0.3s;
}

.book-btn:hover {
    border-color: #db4800;
    color: #db4800;
}

/* ///////////////////////////////////////////////////

HARDCOVER
Table of Contents

1. container
2. background & color
3. opening cover, back cover and pages
4. position, transform y transition
5. events
6. Bonus
    - Cover design
    - Ribbon
    - Figcaption
7. mini-reset

/////////////////////////////////////////////////////*/

/*
    1. container
*/

.book {
    position: relative;
    width: 160px;
    height: 220px;
    -webkit-perspective: 1000px;
    -moz-perspective: 1000px;
    perspective: 1000px;
    -webkit-transform-style: preserve-3d;
    -moz-transform-style: preserve-3d;
    transform-style: preserve-3d;
    margin: 20px;
    margin-bottom: 40px;
    margin-left: 60px;
}

.book ul {
    list-style: none;
}

/*
    2. background & color
*/

/* HARDCOVER FRONT */
.hardcover_front li:first-child {
    background-color: #eee;
    -webkit-backface-visibility: hidden;
    -moz-backface-visibility: hidden;
    backface-visibility: hidden;
}

/* reverse */
.hardcover_front li:last-child {
    background: #fffbec;
}

/* HARDCOVER BACK */
.hardcover_back li:first-child {
    background: #fffbec;
}

/* reverse */
.hardcover_back li:last-child {
    background: #fffbec;
}

.book_spine li:first-child {
    background: #eee;
}

.book_spine li:last-child {
    background: #333;
}

/* thickness of cover */

.hardcover_front li:first-child:after,
.hardcover_front li:first-child:before,
.hardcover_front li:last-child:after,
.hardcover_front li:last-child:before,
.hardcover_back li:first-child:after,
.hardcover_back li:first-child:before,
.hardcover_back li:last-child:after,
.hardcover_back li:last-child:before,
.book_spine li:first-child:after,
.book_spine li:first-child:before,
.book_spine li:last-child:after,
.book_spine li:last-child:before {
    background: #999;
}

/* page */

.page > li {
    background: -webkit-linear-gradient(left, #e1ddd8 0%, #fffbf6 100%);
    background: -moz-linear-gradient(left, #e1ddd8 0%, #fffbf6 100%);
    background: -ms-linear-gradient(left, #e1ddd8 0%, #fffbf6 100%);
    background: linear-gradient(left, #e1ddd8 0%, #fffbf6 100%);
    box-shadow: inset 0px -1px 2px rgba(50, 50, 50, 0.1), inset -1px 0px 1px rgba(150, 150, 150, 0.2);
    border-radius: 0px 5px 5px 0px;
}

/*
    3. opening cover, back cover and pages
*/

.hardcover_front {
    -webkit-transform: rotateY(-34deg) translateZ(8px);
    -moz-transform: rotateY(-34deg) translateZ(8px);
    transform: rotateY(-34deg) translateZ(8px);
    z-index: 100;
}

.hardcover_back {
    -webkit-transform: rotateY(-15deg) translateZ(-8px);
    -moz-transform: rotateY(-15deg) translateZ(-8px);
    transform: rotateY(-15deg) translateZ(-8px);
}

.page li:nth-child(1) {
    -webkit-transform: rotateY(-28deg);
    -moz-transform: rotateY(-28deg);
    transform: rotateY(-28deg);
}

.page li:nth-child(2) {
    -webkit-transform: rotateY(-30deg);
    -moz-transform: rotateY(-30deg);
    transform: rotateY(-30deg);
}

.page li:nth-child(3) {
    -webkit-transform: rotateY(-32deg);
    -moz-transform: rotateY(-32deg);
    transform: rotateY(-32deg);
}

.page li:nth-child(4) {
    -webkit-transform: rotateY(-34deg);
    -moz-transform: rotateY(-34deg);
    transform: rotateY(-34deg);
}

.page li:nth-child(5) {
    -webkit-transform: rotateY(-36deg);
    -moz-transform: rotateY(-36deg);
    transform: rotateY(-36deg);
}

/*
    4. position, transform & transition
*/

.hardcover_front,
.hardcover_back,
.book_spine,
.hardcover_front li,
.hardcover_back li,
.book_spine li {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    -webkit-transform-style: preserve-3d;
    -moz-transform-style: preserve-3d;
    transform-style: preserve-3d;
}

.hardcover_front,
.hardcover_back {
    -webkit-transform-origin: 0% 100%;
    -moz-transform-origin: 0% 100%;
    transform-origin: 0% 100%;
}

.hardcover_front {
    -webkit-transition: all 0.8s ease, z-index 0.6s;
    -moz-transition: all 0.8s ease, z-index 0.6s;
    transition: all 0.8s ease, z-index 0.6s;
}

/* HARDCOVER front */
.hardcover_front li:first-child {
    cursor: default;
    -webkit-user-select: none;
    -moz-user-select: none;
    user-select: none;
    -webkit-transform: translateZ(2px);
    -moz-transform: translateZ(2px);
    transform: translateZ(2px);
}

.hardcover_front li:last-child {
    -webkit-transform: rotateY(180deg) translateZ(2px);
    -moz-transform: rotateY(180deg) translateZ(2px);
    transform: rotateY(180deg) translateZ(2px);
}

/* HARDCOVER back */
.hardcover_back li:first-child {
    -webkit-transform: translateZ(2px);
    -moz-transform: translateZ(2px);
    transform: translateZ(2px);
}

.hardcover_back li:last-child {
    -webkit-transform: translateZ(-2px);
    -moz-transform: translateZ(-2px);
    transform: translateZ(-2px);
}

/* thickness of cover */
.hardcover_front li:first-child:after,
.hardcover_front li:first-child:before,
.hardcover_front li:last-child:after,
.hardcover_front li:last-child:before,
.hardcover_back li:first-child:after,
.hardcover_back li:first-child:before,
.hardcover_back li:last-child:after,
.hardcover_back li:last-child:before,
.book_spine li:first-child:after,
.book_spine li:first-child:before,
.book_spine li:last-child:after,
.book_spine li:last-child:before {
    position: absolute;
    top: 0;
    left: 0;
}

/* HARDCOVER front */
.hardcover_front li:first-child:after,
.hardcover_front li:first-child:before {
    width: 4px;
    height: 100%;
}

.hardcover_front li:first-child:after {
    -webkit-transform: rotateY(90deg) translateZ(-2px) translateX(2px);
    -moz-transform: rotateY(90deg) translateZ(-2px) translateX(2px);
    transform: rotateY(90deg) translateZ(-2px) translateX(2px);
}

.hardcover_front li:first-child:before {
    -webkit-transform: rotateY(90deg) translateZ(158px) translateX(2px);
    -moz-transform: rotateY(90deg) translateZ(158px) translateX(2px);
    transform: rotateY(90deg) translateZ(158px) translateX(2px);
}

.hardcover_front li:last-child:after,
.hardcover_front li:last-child:before {
    width: 4px;
    height: 160px;
}

.hardcover_front li:last-child:after {
    -webkit-transform: rotateX(90deg) rotateZ(90deg) translateZ(80px) translateX(-2px) translateY(-78px);
    -moz-transform: rotateX(90deg) rotateZ(90deg) translateZ(80px) translateX(-2px) translateY(-78px);
    transform: rotateX(90deg) rotateZ(90deg) translateZ(80px) translateX(-2px) translateY(-78px);
}

.hardcover_front li:last-child:before {
    box-shadow: 0px 0px 30px 5px #333;
    -webkit-transform: rotateX(90deg) rotateZ(90deg) translateZ(-140px) translateX(-2px) translateY(-78px);
    -moz-transform: rotateX(90deg) rotateZ(90deg) translateZ(-140px) translateX(-2px) translateY(-78px);
    transform: rotateX(90deg) rotateZ(90deg) translateZ(-140px) translateX(-2px) translateY(-78px);
}

/* thickness of cover */

.hardcover_back li:first-child:after,
.hardcover_back li:first-child:before {
    width: 4px;
    height: 100%;
}

.hardcover_back li:first-child:after {
    -webkit-transform: rotateY(90deg) translateZ(-2px) translateX(2px);
    -moz-transform: rotateY(90deg) translateZ(-2px) translateX(2px);
    transform: rotateY(90deg) translateZ(-2px) translateX(2px);
}

.hardcover_back li:first-child:before {
    -webkit-transform: rotateY(90deg) translateZ(158px) translateX(2px);
    -moz-transform: rotateY(90deg) translateZ(158px) translateX(2px);
    transform: rotateY(90deg) translateZ(158px) translateX(2px);
}

.hardcover_back li:last-child:after,
.hardcover_back li:last-child:before {
    width: 4px;
    height: 160px;
}

.hardcover_back li:last-child:after {
    -webkit-transform: rotateX(90deg) rotateZ(90deg) translateZ(80px) translateX(2px) translateY(-78px);
    -moz-transform: rotateX(90deg) rotateZ(90deg) translateZ(80px) translateX(2px) translateY(-78px);
    transform: rotateX(90deg) rotateZ(90deg) translateZ(80px) translateX(2px) translateY(-78px);
}

.hardcover_back li:last-child:before {
    box-shadow: 10px -1px 80px 20px #666;
    -webkit-transform: rotateX(90deg) rotateZ(90deg) translateZ(-140px) translateX(2px) translateY(-78px);
    -moz-transform: rotateX(90deg) rotateZ(90deg) translateZ(-140px) translateX(2px) translateY(-78px);
    transform: rotateX(90deg) rotateZ(90deg) translateZ(-140px) translateX(2px) translateY(-78px);
}

/* BOOK SPINE */
.book_spine {
    -webkit-transform: rotateY(60deg) translateX(-5px) translateZ(-12px);
    -moz-transform: rotateY(60deg) translateX(-5px) translateZ(-12px);
    transform: rotateY(60deg) translateX(-5px) translateZ(-12px);
    width: 16px;
    z-index: 0;
}

.book_spine li:first-child {
    -webkit-transform: translateZ(2px);
    -moz-transform: translateZ(2px);
    transform: translateZ(2px);
}

.book_spine li:last-child {
    -webkit-transform: translateZ(-2px);
    -moz-transform: translateZ(-2px);
    transform: translateZ(-2px);
}

/* thickness of book spine */
.book_spine li:first-child:after,
.book_spine li:first-child:before {
    width: 4px;
    height: 100%;
}

.book_spine li:first-child:after {
    -webkit-transform: rotateY(90deg) translateZ(-2px) translateX(2px);
    -moz-transform: rotateY(90deg) translateZ(-2px) translateX(2px);
    transform: rotateY(90deg) translateZ(-2px) translateX(2px);
}

.book_spine li:first-child:before {
    -webkit-transform: rotateY(-90deg) translateZ(-12px);
    -moz-transform: rotateY(-90deg) translateZ(-12px);
    transform: rotateY(-90deg) translateZ(-12px);
}

.book_spine li:last-child:after,
.book_spine li:last-child:before {
    width: 4px;
    height: 16px;
}

.book_spine li:last-child:after {
    -webkit-transform: rotateX(90deg) rotateZ(90deg) translateZ(8px) translateX(2px) translateY(-6px);
    -moz-transform: rotateX(90deg) rotateZ(90deg) translateZ(8px) translateX(2px) translateY(-6px);
    transform: rotateX(90deg) rotateZ(90deg) translateZ(8px) translateX(2px) translateY(-6px);
}

.book_spine li:last-child:before {
    box-shadow: 5px -1px 100px 40px rgba(0, 0, 0, 0.2);
    -webkit-transform: rotateX(90deg) rotateZ(90deg) translateZ(-210px) translateX(2px) translateY(-6px);
    -moz-transform: rotateX(90deg) rotateZ(90deg) translateZ(-210px) translateX(2px) translateY(-6px);
    transform: rotateX(90deg) rotateZ(90deg) translateZ(-210px) translateX(2px) translateY(-6px);
}

.page,
.page > li {
    position: absolute;
    top: 0;
    left: 0;
    -webkit-transform-style: preserve-3d;
    -moz-transform-style: preserve-3d;
    transform-style: preserve-3d;
}

.page {
    width: 100%;
    height: 98%;
    top: 1%;
    left: 3%;
    z-index: 10;
}

.page > li {
    width: 100%;
    height: 100%;
    -webkit-transform-origin: left center;
    -moz-transform-origin: left center;
    transform-origin: left center;
    -webkit-transition-property: transform;
    -moz-transition-property: transform;
    transition-property: transform;
    -webkit-transition-timing-function: ease;
    -moz-transition-timing-function: ease;
    transition-timing-function: ease;
}

.page > li:nth-child(1) {
    -webkit-transition-duration: 0.6s;
    -moz-transition-duration: 0.6s;
    transition-duration: 0.6s;
}

.page > li:nth-child(2) {
    -webkit-transition-duration: 0.6s;
    -moz-transition-duration: 0.6s;
    transition-duration: 0.6s;
}

.page > li:nth-child(3) {
    -webkit-transition-duration: 0.4s;
    -moz-transition-duration: 0.4s;
    transition-duration: 0.4s;
}

.page > li:nth-child(4) {
    -webkit-transition-duration: 0.5s;
    -moz-transition-duration: 0.5s;
    transition-duration: 0.5s;
}

.page > li:nth-child(5) {
    -webkit-transition-duration: 0.6s;
    -moz-transition-duration: 0.6s;
    transition-duration: 0.6s;
}

/*
    5. events
*/

@media screen and (min-width: 768px) {
    .book:hover > .hardcover_front {
        -webkit-transform: rotateY(-145deg) translateZ(0);
        -moz-transform: rotateY(-145deg) translateZ(0);
        transform: rotateY(-145deg) translateZ(0);
        z-index: 0;
    }

    .book:hover > .page li:nth-child(1) {
        -webkit-transform: rotateY(-30deg);
        -moz-transform: rotateY(-30deg);
        transform: rotateY(-30deg);
        -webkit-transition-duration: 1.5s;
        -moz-transition-duration: 1.5s;
        transition-duration: 1.5s;
    }

    .book:hover > .page li:nth-child(2) {
        -webkit-transform: rotateY(-35deg);
        -moz-transform: rotateY(-35deg);
        transform: rotateY(-35deg);
        -webkit-transition-duration: 1.8s;
        -moz-transition-duration: 1.8s;
        transition-duration: 1.8s;
    }

    .book:hover > .page li:nth-child(3) {
        -webkit-transform: rotateY(-118deg);
        -moz-transform: rotateY(-118deg);
        transform: rotateY(-118deg);
        -webkit-transition-duration: 1.6s;
        -moz-transition-duration: 1.6s;
        transition-duration: 1.6s;
    }

    .book:hover > .page li:nth-child(4) {
        -webkit-transform: rotateY(-130deg);
        -moz-transform: rotateY(-130deg);
        transform: rotateY(-130deg);
        -webkit-transition-duration: 1.4s;
        -moz-transition-duration: 1.4s;
        transition-duration: 1.4s;
    }

    .book:hover > .page li:nth-child(5) {
        -webkit-transform: rotateY(-140deg);
        -moz-transform: rotateY(-140deg);
        transform: rotateY(-140deg);
        -webkit-transition-duration: 1.2s;
        -moz-transition-duration: 1.2s;
        transition-duration: 1.2s;
    }
}

/*
    6. Bonus
*/

/* cover CSS */

.coverDesign {
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    overflow: hidden;
    -webkit-backface-visibility: hidden;
    -moz-backface-visibility: hidden;
    backface-visibility: hidden;
}

.coverDesign::after {
    background-image: -webkit-linear-gradient(-135deg, rgba(255, 255, 255, 0.45) 0%, transparent 100%);
    background-image: -moz-linear-gradient(-135deg, rgba(255, 255, 255, 0.45) 0%, transparent 100%);
    background-image: linear-gradient(-135deg, rgba(255, 255, 255, 0.45) 0%, transparent 100%);
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
}

.coverDesign h1 {
    color: #fff;
    font-size: 2.2em;
    letter-spacing: 0.05em;
    text-align: center;
    margin: 54% 0 0 0;
    text-shadow: -1px -1px 0 rgba(0, 0, 0, 0.1);
}

.coverDesign p {
    color: #f8f8f8;
    font-size: 1em;
    text-align: center;
    text-shadow: -1px -1px 0 rgba(0, 0, 0, 0.1);
}

.yellow {
    background-color: #f1c40f;
    background-image: -webkit-linear-gradient(top, #f1c40f 58%, #e7ba07 0%);
    background-image: -moz-linear-gradient(top, #f1c40f 58%, #e7ba07 0%);
    background-image: linear-gradient(top, #f1c40f 58%, #e7ba07 0%);
}

.blue {
    background-color: #3498db;
    background-image: -webkit-linear-gradient(top, #3498db 58%, #2a90d4 0%);
    background-image: -moz-linear-gradient(top, #3498db 58%, #2a90d4 0%);
    background-image: linear-gradient(top, #3498db 58%, #2a90d4 0%);
}

.grey {
    background-color: #f8e9d1;
    background-image: -webkit-linear-gradient(top, #f8e9d1 58%, #e7d5b7 0%);
    background-image: -moz-linear-gradient(top, #f8e9d1 58%, #e7d5b7 0%);
    background-image: linear-gradient(top, #f8e9d1 58%, #e7d5b7 0%);
}

/* Basic ribbon */

.ribbon {
    background: #c0392b;
    color: #fff;
    display: block;
    font-size: 0.7em;
    position: absolute;
    top: 11px;
    right: 1px;
    width: 40px;
    height: 20px;
    line-height: 20px;
    letter-spacing: 0.15em;
    text-align: center;
    -webkit-transform: rotateZ(45deg) translateZ(1px);
    -moz-transform: rotateZ(45deg) translateZ(1px);
    transform: rotateZ(45deg) translateZ(1px);
    -webkit-backface-visibility: hidden;
    -moz-backface-visibility: hidden;
    backface-visibility: hidden;
    z-index: 10;
}

.ribbon::before,
.ribbon::after {
    position: absolute;
    top: -20px;
    width: 0;
    height: 0;
    border-bottom: 20px solid #c0392b;
    border-top: 20px solid transparent;
}

.ribbon::before {
    left: -20px;
    border-left: 20px solid transparent;
}

.ribbon::after {
    right: -20px;
    border-right: 20px solid transparent;
}

/* figcaption */

.book figcaption {
    padding-left: 40px;
    padding-top: 40px;
    text-align: left;
    position: absolute;
    top: 0%;
    left: 160px;
    width: 500px;
}

.book figcaption h1 {
    margin: 0;
}

.book figcaption span {
    color: #245f78;
    padding: 0.6em 0 0.2em 0;
    display: block;
}

.book figcaption p {
    color: black;
    line-height: 1.3;
}

/* Media Queries */
@media screen and (max-width: 767px) {
    .align > li {
        width: 100%;
        min-height: 440px;
        height: auto;
        padding: 0;
        margin: 0 0 30px 0;
    }

    .book {
        margin-left: 60px;
        display: block;
        margin-bottom: 280px;
    }

    .book figcaption {
        min-width: 320px;
        top: 250px;
        padding-left: 0;
        left: -60px;
        display: block;
    }
}

@media screen and (max-width: 550px) {
    .book {
        height: 250px;
    }

    .book figcaption {
        width: 320px;
    }
}