Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.21)
// Compass (v1.0.3)
// ----

@mixin responsive-calc($columns: 2, $under: 480px) {
  $pre-computed-calc: #{($under * ($under / 1px))} - #{(100% * ($under / 1px))};

  display: inline-block;
  min-width: ($under / 2);
  width: (100% / $columns);
  max-width: 100%;
  min-width: -webkit-calc(100% / #{$columns});
  min-width: calc(100% / #{$columns});
  width: -webkit-calc(#{$pre-computed-calc});
  width: calc(#{$pre-computed-calc});
}

.foo {
  @include responsive-calc($columns: 3, $under: 600px);
}

SassMeister-output.css

.foo {
  display: inline-block;
  min-width: 300px;
  width: 33.33333333%;
  max-width: 100%;
  min-width: -webkit-calc(100% / 3);
  min-width: calc(100% / 3);
  width: -webkit-calc(360000px - 60000%);
  width: calc(360000px - 60000%);
}