10. Red and Blue Together are Hard on the Eyes

Don’t ever design blue text on a red background. Ever. And don’t put green on red, either. A visual phenomenon, called chromostereopsis, makes our eyes want to turn a 2D image into something 3D. But our eyes can’t actually do it. The blue or green tries to recess into the background, but then they try to jump back into the foreground. It’s enough to give anyone a headache. So don’t do it. Never put blue or green text on a red background or red on a blue or green background. Ever.