为什么小程序不能渲染last-chid伪类

.comment::after{

  content: “”;

  display: block;

  position: absolute;

  bottom: 0;

  left: 0;

  right: 0;

  height: 1px;

  border-bottom:1rpx solid #ddd;

  margin-left: 15px;

}

.comment:last-child::after{

  display: none!important;

}

 没有效果