Ref for libsass issue

SassMeister-input.scss

// ----
// Sass (v3.3.0.rc.3)
// Compass (v1.0.0.alpha.18)
// ----

@mixin hidpi($num, $denom: 1) {
  @media
  (-webkit-min-device-pixel-ratio: $num/$denom),
  (min--moz-device-pixel-ratio: $num/$denom),
  (-o-min-device-pixel-ratio: #{$num}/#{$denom}),
  (min-device-pixel-ratio: $num/$denom),
  (min-resolution: $num/$denom * 96dpi),
  (min-resolution: $num/$denom * 1dppx) {
    @content;
  }
}

.test {
  @media only screen and (min-width: 700px) {
    @include hidpi(3,2) {
      color: red;
    }
  }
}

SassMeister-output.css

@media only screen and (min-width: 700px) and (-webkit-min-device-pixel-ratio: 1.5), only screen and (min-width: 700px) and (min--moz-device-pixel-ratio: 1.5), only screen and (min-width: 700px) and (-o-min-device-pixel-ratio: 3 / 2), only screen and (min-width: 700px) and (min-device-pixel-ratio: 1.5), only screen and (min-width: 700px) and (min-resolution: 144dpi), only screen and (min-width: 700px) and (min-resolution: 1.5dppx) {
  .test {
    color: red; } }

written as reference for a libsass issue