Change text color based on background. Color is a darker/lighter hue of background.

dynamic-text-color.scss

// Grab brightness of color
@function brightness($color) {
  @return ((red($color)) + (green($color)) + (blue($color))) / 255 * 100%;
}
 
// Compare bightness and print new text color
@function text-color($color) {
  @if $color == null {
    @return null;
  }
  @else {
    $color-light: mix(#ffffff, $color, 80%);
    $color-dark: mix(#000000, $color, 60%);
    $color-brightness: brightness($color);
    $light-text-brightness: brightness($color-light);
    $dark-text-brightness: brightness($color-dark);
 
    @if abs($color-brightness - $light-text-brightness) > abs($color-brightness - $dark-text-brightness) {
      @return $color-light;
    }
    @else {
      @return $color-dark;
    }
  }
}