Rem Sass mixin (originally by @BPScott)

rem-mixin.scss

// Rems with pixel fallback for any property
// @author @BPScott (https://github.com/BPScott/bpscott.github.io/blob/develop/source/stylesheets/vendor/_rem.scss)
@mixin rem($property, $px-values, $baseline-px: $base-font-size) {
  // Convert the baseline into rems
  $baseline-rem: $baseline-px / 1rem;

  // Create an empty list that we can dump values into
  $rem-values: ();
  @each $value in $px-values {
        // If the value is zero, return 0
        $rem-values: append($rem-values, if($value == 0, $value, $value / $baseline-rem));
  }

  // Output the property's px and rem values
  #{$property}: $px-values;
  #{$property}: $rem-values;
}