css給列表添加序號

.middle ul{
    counter-reset: show-list;
}
li{
    padding-left: 30px;
    line-height: 1.3;
    position: relative;
    counter-increment: item;
}
li:before{
    content: counter(item)".";
    display: block;
    position: absolute;
    left: 12px;
    top:0;
}