_shared.scss

@mixin pseudo-elem {
  content: '';
  display: block;
  height: 100%;
  width: 100%;
  top: 0;
  left: 0;
  position: absolute;
  pointer-events: none;
}

@mixin filter-base {
  position: relative;

  img {
    width: 100%;
    z-index: 1;
  }

  &:before {
    @include pseudo-elem;
    z-index: 2;
  }

  &:after {
    @include pseudo-elem;
    z-index: 3;
  }
}