To translate contrast, it uses a numerical model. If the text and background of a website are the same color, the ratio is 1:1. For black text on white background (or vice versa), the ratio is 21:1.

Want to switch to Dark Mode in Office ... it had too high a contrast color. Many found it as a challenge to even sit in front of the bright background of Office and use it for a few hours.

And the rehang at the National Gallery departs from red and green spectacularly in places, and particularly in the Renaissance section, where the paintings are radiant—against walls of dark blue.