thoughtbot/bourbon

@charset "UTF-8";

/// Programatically determines the lightness of a color.
///
/// @argument {color (hex)} $hex-color
///
/// @return {number (0-1)}
///
/// @example scss
///   _lightness($color)
///
/// @access private

@use "sass:math";

@function _lightness($hex-color) {
  $-local-red-raw: red(rgba($hex-color, 1));
  $-local-green-raw: green(rgba($hex-color, 1));
  $-local-blue-raw: blue(rgba($hex-color, 1));

  $-local-red: _gamma(math.div($-local-red-raw, 255));
  $-local-green: _gamma(math.div($-local-green-raw, 255));
  $-local-blue: _gamma(math.div($-local-blue-raw, 255));

  @return $-local-red * 0.2126 + $-local-green * 0.7152 + $-local-blue * 0.0722;
}