css 三角形

.***:after {
    content: "";
    width: 0;
    height: 0;
    position: absolute;
    right: 16px;
    top: 50%;
    margin-top: -6px;
    border-width: 6px 0 6px 6px;
    border-style: solid;
    border-color: transparent #fff;
}