.slider { height:440px; background-color:#18a4a4; padding-top: 60px; margin-top:2px; }
@media only screen and (max-width: 600px) {
    .slider {
        display: none;
    }
}
.book_title {  border-bottom: solid 1px #ccc; padding-bottom: 10px; }
.book_info { line-height:100%; margin:10px 20px; }
.book_info .title { display: inline-block; width: 100px; font-weight: bold; }
.download { color: green; margin-top: 30px; }
.book_sale { margin-left: 20px; border-top:solid 1px #ccc; padding-top:30px; }
.book_intro { border-top:solid 1px #ccc; }
.book_intro .title { font-size: 1.2rem; font-weight: bold; }
.book_intro .content { line-height: 180%; }