// @charset "UTF-8";

@mixin background-image-retina($file, $type, $width, $height) {
  background-image: unquote(image-url("#{$file}.#{$type}"));

  @media (-webkit-min-device-pixel-ratio: 2), (-moz-min-device-pixel-ratio: 2) {
    & {
      background-image: image-url("#{$file}@2x.#{$type}");
      -webkit-background-size: $width $height;
    }
  }
}

$x: foo;
$y: bar;

div {
  @include background-image-retina(test, png, 100px, 300px);
  fudge: walnut;
}

span {
  blah: "#{$x} #{$y}";
  bleh: image-url("#{$x} #{$y}");
}