.books {
    margin:0;
    padding:0;
    display:flex;
    flex-direction:column;
    justify-content: space-between;
    align-items:center;
    width:100vw;
    height:100vh;
    background-color:#dcedff!important;
    
}
.book1{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    width:100vw;
    height: 40vw;
    display: flex;
    flex-direction:row;
    justify-content: center;
    align-items: center;
    font-family: sans-serif;
}
.book2{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    width:100vw;
    height: 40vw;
    display:none;
    flex-direction:row;
    justify-content: center;
    align-items: center;
    font-family: sans-serif;
}
.book-switch {
    margin:0;
    padding:0;
    display:flex;
    flex-direction: row;
    justify-content:center;
    align-items: center;
    height: 10%;
}
.button {
    position: relative;
    width: 13vw;
    height: 3vw;
    overflow: hidden;
    border-radius: 3vw;
    font-family: 'IBM Plex Sans'
}
.checkbox {
    position: relative;
    width: 100%;
    height: 100%;
    padding: 0;
    margin: 0;
    opacity: 0;
    cursor: pointer;
    z-index: 3;
}
.knobs, .layer {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
}
.knobs {
    z-index: 2;
}
.layer {
    width: 100%;
    transition: 0.3s ease all;
    z-index: 1;
}

/* Button Change*/
.knobs:before,
.knobs:after {
    position: absolute;
    width: 6vw;
    height: 2.2vw;
    color: #fff;
    font-size: 1.1vw;
    font-weight: bold;
    text-align: center;
    line-height: 1;
    padding-top:0.6vw;
    border-radius: 3vw;
    transition: 0.3s cubic-bezier(0.18, 0.89, 0.35, 1.15) all;
}
.knobs:before {
    content: "English";
    top: .4vw;
    left:.8vw;
    background-color: #f77587;
}
.knobs:after {
    content: "Chinese";
    top: -10vw;
    right: .8vw;
    left: auto;
    background-color: #513681;
}

.checkbox:checked + .knobs:before {
    top: -10vw;
}

.checkbox:checked + .knobs:after {
    top: .4vw;
}

.checkbox:checked ~ .layer {
    background-color: #bba9db;
}
.checkbox ~ .layer {
    background-color: white;
}