伪元素before after有区别吗？我加before 和after都只能在div下方添加横线？

 .WxBookContentEdit .FormItemListEdit2:after {
    content: " ";
    position: absolute;
    left: -8px;
    bottom: 0px;
    right: -25px;
    border-bottom: 1px solid #d9d9d9;
    color: #d9d9d9;
    -webkit-transform-origin: 0 100%;
    transform-origin: 0 100%;
    -webkit-transform: scaleY(0.5);
    transform: scaleY(0.5);
    z-index: 5;
}

http://blog.dimpurr.com/css-before-after/