Simple library for checking the contrast between two colors. Checks contrast ratio according to the [WCAG 2](https://www.w3.org/TR/WCAG20/#contrast-ratiodef) (corrected to use 0.04045 instead of 0.03928.
Used in [Tetratto](https://github.com/trisuaso/tetratto) to show people when their custom themes are absolutely awful.