@charset "UTF-8";

/// Mixes a color with black.
///
/// @argument {color} $color
///
/// @argument {number (percentage)} $percent
///   The amount of black to be mixed in.
///
/// @return {color}
///
/// @example scss
///   .element {
///     background-color: shade(#ffbb52, 60%);
///   }
///
///   // CSS Output
///   .element {
///     background-color: #664a20;
///   }

@function shade(
    $color,
    $percent
  ) {

  @if not _is-color($color) {
    @error "`#{$color}` is not a valid color for the `$color` argument in " +
           "the `shade` mixin.";
  } @else {
    @return mix(#000, $color, $percent);
  }
}