/* 1个像素的边框 */
$border {
  position: absolute;
  content: ' ';
  top: 0;
  left: 0;
  -webkit-transform-origin: top left;
  transform-origin: top left;
  width: 100%;
  height: 100%;
  -webkit-transform: scale(1);
  transform: scale(1);
  pointer-events: none;

  for $i in 2 .. 3 {
    @media (-webkit-min-device-pixel-ratio: $i), (min-device-pixel-ratio: $i) {
      width: $i * 100 + '%';
      height: $i * 100 + '%';
      -webkit-transform: scale((1 / $i));
      transform: scale((1 / $i));
    }
  }
}

/* 下边框 */
border1px-bottom($border-color = #cccccc, $border-style = solid) {
  position: relative;

  &:after {
    border-bottom: 1px $border-style $border-color;
    @extend $border;
  }
}