Fluid sizes | Zach Schnackel

Often times when working with responsive projects, we tend to forget that typography doesn't automatically scale down on smaller screens. While there are other solutions out there; like rem to universally control this, having more flexibility can be warranted.

I came across a pretty great mixin for Sass that allowed me to attach this functionality to specific selectors:

///
/// @param {variable} $min-font-size [12px] - Minimum font size
/// @param {variable} $max-font-size [24px] - Maximum font size
/// @param {variable} $lower-range [480px] - Stop scaling font smaller at this screen resolution
/// @param {variable} $upper-range [960px] - Stop scaling font larger at this screen resolution
/// @source https://madebymike.com.au/writing/precise-control-responsive-typography/
///
@mixin fluid-type(
  $min-font-size: 12px,
  $max-font-size: 24px,
  $lower-range: 480px,
  $upper-range: 960px
) {
  font-size:
    calc(
      #{$min-font-size} + #{(
        ($max-font-size / ($max-font-size * 0 + 1)) -
        ($min-font-size / ($min-font-size * 0 + 1))
      )} * ((100vw - #{$lower-range}) / #{(
        ($upper-range / ($upper-range * 0 + 1)) -
        ($lower-range / ($lower-range * 0 + 1))
      )})
    );
 
  @media (max-width: $lower-range) {
    font-size: $min-font-size !important;
  }
 
  @media (min-width: $upper-range) {
    font-size: $max-font-size !important;
  }
 
// Example
.selector {
  @include fluid-type(
    15px,
    20px
  );
}

The above snippet had me thinking about how I could apply this to any property that I wanted to have scalable values. Thus, the below was created:

///
/// @param {variable} $property [font-size]
/// @param {variable} $min-size [12px]
/// @param {variable} $max-size [24px]
/// @param {variable} $lower-range [480px] - Stop scaling smaller at this screen resolution
/// @param {variable} $upper-range [960px] - Stop scaling larger at this screen resolution
///
@mixin fluid-size(
  $property: 'font-size',
  $min-size: 12px,
  $max-size: 24px,
  $lower-range: 480px,
  $upper-range: 960px
) {
  #{$property}: calc(
    #{$min-size} + #{(
        ($max-size / ($max-size * 0 + 1)) - ($min-size / ($min-size * 0 + 1))
      )} *
      (
        (100vw - #{$lower-range}) / #{(
            ($upper-range / ($upper-range * 0 + 1)) - ($lower-range /
                  ($lower-range * 0 + 1))
          )}
      )
  );
 
  @media (max-width: $lower-range) {
    #{$property}: $min-size !important;
  }
 
  @media (min-width: $upper-range) {
    #{$property}: $max-size !important;
  }
}
 
// Example
.selector {
  @include fluid-size('padding', 100px, 200px);
}

This helps clean up common UI elements even further; making my source a bit cleaner as well. Huzzah!