Add Contrast Ratio Calculation

[peterquale]

Hello! Your tool is fantastic for grabbing colors to test WCAG color contrast requirements. I believe if you added a simple ratio calculator between the two colors, you'd get a lot of users looking for that feature. Most tools available now are pretty tedious like this:

https://webaim.org/resources/contrastchecker/

Thanks for making this! Keep up the good work.

[kepi]

Thanks for great idea, I'll try to implement this when I find couple hours.