Why is there no mention of chromatic aberration?<p>I understand that blue makes a good background because usually in a normal human eye blue will be defocused.<p><a href="https://www.nature.com/articles/s41598-020-79911-w" rel="nofollow noreferrer">https://www.nature.com/articles/s41598-020-79911-w</a>
Good contrast. True, better contrast still is yellow-on-black, but that always appears too harsh to the eye.<p>The yellow-on-blue gives both good contrast, and softness to the eye.