hr标签如何做成这种效果？

Question

Answer 1

<hr class="hr">

.hr{
    position: relative;
}
.hr:after{
    content: "";
    position: absolute;
    top: 0;left: 0;right: 0;bottom: 0;
    margin: auto;
    display: block;
    border: 1px solid #ccc;
    height: 10px;
    width: 10px;
    background-color: #fff;
}