foundation-sites/scss/prototype/_sizing.scss

// Foundation for Sites by ZURB
// foundation.zurb.com
// Licensed under MIT Open Source

////
/// @group prototype-sizing
////

/// Responsive breakpoints for spacing classes (margin and padding)
/// @type Boolean
$prototype-sizing-breakpoints: $global-prototype-breakpoints !default;

/// Map containing all the `sizing` classes
/// @type Map
$prototype-sizing: (
  width,
  height
) !default;

/// Map containing all the sizes.
/// @type Map
$prototype-sizes: (
  25: 25%,
  50: 50%,
  75: 75%,
  100: 100%
) !default;

/// Max Width 100 utility.
@mixin max-width-100 {
  max-width: 100% !important;
}

/// Max Height 100 utility.
@mixin max-height-100 {
  max-height: 100% !important;
}

@mixin foundation-prototype-sizing {
  // Element Sizing
  @each $sizing in $prototype-sizing {
    @each $length, $percentage in $prototype-sizes {
      .#{$sizing}-#{$length} {
        #{$sizing}: $percentage !important;
      }
    }
  }

  // Max width & height
  .max-width-100 {
    @include max-width-100;
  }
  .max-height-100 {
    @include max-height-100;
  }

  @if ($prototype-sizing-breakpoints) {
    // Loop through Responsive Breakpoints
    @each $size in $breakpoint-classes {
      @include breakpoint($size) {
        @if $size != $-zf-zero-breakpoint {
          @each $sizing in $prototype-sizing {
            @each $length, $percentage in $prototype-sizes {
              .#{$size}-#{$sizing}-#{$length} {
                #{$sizing}: $percentage !important;
              }
            }
          }
        }
      }
    }
  }
}