.book{
    padding:3px 0 0;margin:auto}
.shelf
{
    border-bottom:30px solid #a5a5a5;
    border-left:20px solid transparent;
    border-right:20px solid transparent;
    top:-20px;z-index:-10;margin-bottom:50px
}
.shelf:after{
    content:'';
    background:url(concrete_bg_dark.jpg) top left repeat-x #686868;
    height:20px;width:calc(100% + 40px);
    position:absolute;top:30px;left:0;right:0;z-index:4;margin:0 -20px
}