Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.10)
// Compass (v1.0.0.alpha.20)
// Susy (v2.1.2)
// ----

@import "susy";

@mixin mq-layout(
  $mq,
  $layout: $susy
) {
  $mq: if(type-of($mq) == number, 'min-width: #{$mq}', $mq);
  @media ($mq) {
    @include with-layout($layout) {
      @content;
    }
  }
}

.test {
  @include span(4);
  @include mq-layout(45em, 12) {
    @include span(4);
  }
}

SassMeister-output.css

.test {
  width: 100%;
  float: left;
  margin-left: 0;
  margin-right: 0;
}
@media (min-width: 45em) {
  .test {
    width: 32.20339%;
    float: left;
    margin-right: 1.69492%;
  }
}