Ever want to test the lightness of a color with Sass? You can do that. An example use case would be a mixin for button defaults. Test the lightness of the background to determine what color the text should be.
// Test lightness of background @if lightness($color) > lightness(#aaa) color: darken($color, 75%) @ else color: $white
Note: A space was added between "@" and "else" as a workaround to Coderwall's attempt at auto linking what it deems to be an @mention.