section {
    background-color: #ffffff;
    padding-bottom:70px;
}
section:nth-child(2n-1) {
    background-color: #dcdcdc;
}
.books {
    display: none;
    animation-duration: 2s;
    animation-name: fadein;
    width: 1000px;
    margin: 0 auto;
}
.books.show {
    display: block;
}
@keyframes fadein {
  0% {
    opacity: 0;
  }
  100% {
    opacity: 1;
  }
}
h2 {
    padding-top:55px;
    margin: 0 auto 50px;
}
ul.book_menu {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-around;
    width: 800px;
    margin: 70px auto 30px;
    padding-left: 160px;
    font-size: 1.3rem;
}
ul.book_menu li {
    width:50%;
    margin:8px 0;
    cursor: pointer;
}
ul.book_menu li::before {
    content: "";
    display: inline-block;
    width:18px;
    height:20px;
    background-image: url(../img/common/arrow2.png);
    background-size: contain;
    background-repeat: no-repeat;
    position: relative;
    top:5px;
}
ul.book_menu li a {
    padding-left: 10px;
}
.subchara {
    justify-content: space-evenly;
    margin: 20px auto;
}
.subchara h5 {
    font-size: 18px;
}

@media screen and (max-width: 500px) {
    section {
        padding-bottom:0;
    }
    .books {
        width:96%;
    }
    ul.book_menu {
        width: 80%;
        padding: 0;
        font-size: 1.1rem;
        display: block;
        margin: 10px auto 30px;
    }
    ul.book_menu li {
        width:100%;
    }
}