实现移动端1像素线--stylus

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;