It’s a common part of automated accessibility testing in web ui programming. You just click a button, and your entire site is examined, every instance of one co

It’s a common part of automated accessibility testing in web ui programming. You just click a button, and your entire site is examined, every instance of one colour of content against another colour in the background is graded according to the contrast ratio between the two colours. If the colours are too close, it lets you know, so you can change it.