伪类实现 移动端1px 细线

/*手机端实现真正的一像素边框*/
.border-1px, .border-bottom-1px, .border-top-1px, .border-left-1px, .border-right-1px {
   position: relative;
 }
/*线条颜色 黑色*/
.border-1px::after, .border-bottom-1px::after, .border-top-1px::after, .border-left-1px::after, .border-right-1px::after {
     background-color: #000; 

}

 /*底边边框一像素*/
.border-bottom-1px::after {
     content:"";
     position: absolute;
     left: 0;
     bottom: 0;
     width: 100%;
     height: 1px;
     transform-origin: 0 0;
 }

 /*上边边框一像素*/
.border-top-1px::after {
   content:"";
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 1px;
    transform-origin: 0 0;
}

 /*左边边框一像素*/
.border-left-1px::after {
  content:"";
  position: absolute;
  left: 0;
  top: 0;
  width: 1px;
  height: 100%;
  transform-origin: 0 0;
 }

/*右边边框1像素*/
.border-right-1px::after {
          content: "";
          box-sizing: border-box;
          position: absolute;
          right: 0;
          top: 0;
          width: 1px;
          height: 100%;
          transform-origin: 0 0;
 }

/*边框一像素*/
.border-1px::after {
  content: "";
  box-sizing: border-box;
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  border: 1px solid red;
}

/*设备像素比*/
@media only screen and (-webkit-min-device-pixel-ratio: 2.0), only screen and (min-resolution: 2dppx) {
    .border-bottom-1px::after, .border-top-1px::after {
      transform: scaleY(0.5);
    }  

   .border-left-1px::after, .border-right-1px::after {

       transform: scaleX(0.5);
    }
   .border-1px::after {
          width: 200%;
          height: 200%;
          transform: scale(0.5);
            transform-origin: 0 0;
     }
}

/*设备像素比*/
@media only screen and (-webkit-min-device-pixel-ratio: 3.0), only screen and (min-resolution: 3dppx) {
   .border-bottom-1px::after, .border-top-1px::after {
      transform: scaleY(0.333);
   }
   .border-left-1px::after, .border-right-1px::after {
     transform: scaleX(0.333);
   }
  .border-1px::after {
      width: 300%;
      height: 300%;
      transform: scale(0.333);
      transform-origin: 0 0;
  }
}

原文地址：https://www.cnblogs.com/cuikaitong/p/9670176.html