// Resolution Mediaqueries
.hdpi(@ratio: 1.5, @ruleset: default) {
  & when (isnumber(@ratio)) {
    @media
    (-webkit-min-device-pixel-ratio: @ratio),
    (min-resolution: (round(@ratio * 96dpi))) {
      @ruleset();
    }
  }

  & when (isruleset(@ratio)) {
    @media
    (-webkit-min-device-pixel-ratio: 1.5),
    (min-resolution: 144dpi) {
      @ratio();
    }
  }
}

.x2(@ruleset: default) {
  .hdpi(2, @ruleset);
}

.x3(@ruleset: default) {
  .hdpi(3, @ruleset);
}