border($border-width = 1px, $border-color = #ccc, $border-style = solid, $radius = 0)

  // 为边框位置提供定位参考

  position: relative;

  if $border-width == null

    $border-width: 0;

  border-radius: $radius;

  &::after

    // 用以解决边框layer遮盖内容

    pointer-events: none;

    position: absolute;

    z-index: 999;

    top: 0;

    left: 0;

    // fix当元素宽度出现小数时，边框可能显示不全的问题

    // overflow: hidden;

    content: "\0020";

    border-color: $border-color;

    border-style: $border-style;

    border-width: $border-width;

    // 适配dpr进行缩放

    @media (max--moz-device-pixel-ratio: 1.49), (-webkit-max-device-pixel-ratio: 1.49), (max-device-pixel-ratio: 1.49), (max-resolution: 143dpi), (max-resolution: 1.49dppx)

      width: 100%;

      height: 100%;

      if $radius != null {

        border-radius: $radius;

      }

    @media (min--moz-device-pixel-ratio: 1.5) and (max--moz-device-pixel-ratio: 2.49), (-webkit-min-device-pixel-ratio: 1.5) and (-webkit-max-device-pixel-ratio: 2.49),(min-device-pixel-ratio: 1.5) and (max-device-pixel-ratio: 2.49),(min-resolution: 144dpi) and (max-resolution: 239dpi),(min-resolution: 1.5dppx) and (max-resolution: 2.49dppx)

      width: 200%;

      height: 200%;

      transform: scale(.5)

      if $radius != null {

        border-radius: $radius * 2;

      }

    @media (min--moz-device-pixel-ratio: 2.5), (-webkit-min-device-pixel-ratio: 2.5),(min-device-pixel-ratio: 2.5), (min-resolution: 240dpi),(min-resolution: 2.5dppx)

      width: 300%;

      height: 300%;

      transform: scale(.33333)

      if $radius != null {

        border-radius: $radius * 3;

      }

    transform-origin: 0 0;