$border-poses: top, right, bottom, left;

@define-mixin border-retina $poses: $border-poses, $border-retina-color: #e5e5e5 {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  box-sizing: border-box;
  width: 200%;
  height: 200%;
  transform: scale(.5);
  transform-origin: left top;
  -webkit-perspective: 1000;
  -webkit-backface-visibility: hidden;
  pointer-events: none;

  @each $pos in $poses {
    border-$(pos): 1px solid $border-retina-color;
  }
}