before和after

竖线：
.aa:before {
    content: '';
    position: absolute;
    left: 0; 
    top: 0.83rem;
    height: .8rem;
    width: 1px;
    margin-left: -0.55rem;
    display: block;
    border-left: 1px solid #f7817d;/** #3499e6;*/
    z-index: 15;
}
横线：
.bb:after{
    content: '';
    position: absolute;
    left: 50%;
    transform: translate(-50%,0);
    bottom: -.22rem;
    width: 1.5rem;
    height: 1px;
    display: block;
    border-bottom: 2px solid #42A0E2;
    z-index: 15;
}

详细资料：
https://www.cnblogs.com/starof/p/4459991.html