使用偽類處理移動端1px（1像素）邊框問題

.box{
    position: relative;
    border: none;
}

.box:after{  //  單邊框
    content: '';
    position: absolute;
    bottom: 0;
    background: #DCDCDC;
    width: 100%;
    height: 1px;
    -webkit-transform: scaleY(0.5);
    transform: scaleY(0.5);
    -webkit-transform-origin: 0 0;
    transform-origin: 0 0;
}

.box:after{  //   四條邊框
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  border: 1px solid #000;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
  width: 200%;
  height: 200%;
  -webkit-transform: scale(0.5);
  transform: scale(0.5);
  -webkit-transform-origin: left top;
  transform-origin: left top;
}