// Programatically determines whether a color is light or dark
// Returns a boolean
// More details here http://robots.thoughtbot.com/closer-look-color-lightness

@function is-light($hex-color) {
  $red: red(rgba($hex-color, 1.0));
  $green: green(rgba($hex-color, 1.0));
  $blue: blue(rgba($hex-color, 1.0));

  $lightness: ($red * 0.2126 + $green * 0.7152 + $blue * 0.0722) / 255;

  @return $lightness > .6;
}