User blog comment:Rupert Giles/Layout Changes: Breakpoints and Typography/@comment-13918697-20150527072158/@comment-5558012-20150529233020

The colors don't mean something is broken unless you know what selector (as 452 described) you should have isn't what you do have or you see a large red section of text. They are more to see the differences between text in a common family (ie. selectors, measurement units, etc).