从 0 开始，vue 饿了么项目 mixin.less

assets/less/mixin.less

.border-1px(@color){
  position: relative;
    &:after{
      display: block;
      position: absolute;
      left: 0;
      bottom:0;
      width: 100%;
      border-top: 1px solid @color;
      content: '';
    }
}

.bg-image(@url){
  background-image:~"url(@{url}@2x.png)";
  @media (-webkit-min-device-pixel-ratio: 3),(min-device-pixel-ratio: 3){
    background-image:~"url(@{url}@3x.png)";
  }
}