A modified version of https://github.com/NickColley/contrast-checker by Nick Colley that adds logic for Alpha channels
Demo app: https://contrast-checker-alpha.netlify.app/ Logic implemented based on this discussion: https://stackoverflow.com/questions/2049230/convert-rgba-color-to-rgb Full Theory: https://en.wikipedia.org/wiki/Alpha_compositing
Check contrast with the new WCAG 2.1 requirements. Original design by Dave House.