@function tint($color, $percentage) {
  @return mix(white, $color, $percentage);
}

@function shade($color, $percentage) {
  @return mix(black, $color, $percentage);
}

@function negativify-map($map) {
  $result: ();

  @each $key, $value in $map {
    @if $key != 0 {
      $result: map-merge($result, ($key: (-$value)));
    }
  }

  @return $result;
}