_bg-color.scss

@mixin bg-color($color, $darken) {
  // local variables
  $background-color: darken($color, $darken);
  $lightness: lightness($background-color);

  // calculate text color variable
  @if $lightness < 50 {
    $text-color: lighten($background-color, 15);
    $background-color: desaturate($background-color, 7);
    background: $background-color;
    color: $text-color;
  }
  @else {
    $text-color: darken($background-color, 15);
    $background-color: desaturate($background-color, 6);
    background: $background-color;
    color: $text-color;
  }
}