关于 1px

.setTopLine(@c: #DCDCDC) {  content: " ";  position: absolute;  left: 0;  top: 0;  right: 0;  height: 1px;  border-top: 1px solid @c;  color: @c;  transform-origin: 0 0;  transform: scaleY(0.5);}

&:before {        content: " ";        .setTopLine();      }