@mixin onlyFirefox {
  @media screen and (min--moz-device-pixel-ratio:0) {
    @content;
  }
}

@mixin onlySafari {
  @media not all and (min-resolution: 0.001dpcm) {
    @content;
  }
}

@mixin onlySafariAndFirefox {
  @media not all and (min-resolution: 0.001dpcm) {
    @content;
  }
  @media screen and (min--moz-device-pixel-ratio:0) {
    @content;
  }
}