Why should I be concerned about color contrast?
Contrast and color use are vital to accessibility. Students, including those with visual disabilities, must be able to perceive content on the page. Accessible color contrast helps students to easily focus on the content rather than the distraction of color. It also allows those without a color printer to print off documents and still understand important areas. This content can be easily moved from different document file types and computers without losing highlighted portions.
Best practices
Contrast Ratio: The measured perceived difference of two colors. The minimum contrast ratio suggested is 4.5:1, which means, the contrast of words on the page (smaller than 18-point font) should have a ratio of at least 4.5:1. Large text is easier to read (text that is 18 point and larger, or 14 point and larger if it is bold), so the minimal contrast ratio is 3:1.
Color alone should not indicate important content or instructions. You can use color to reinforce information, as long as color is not the only way this status is presented (for example, using red shaded cells in a table indicating late assignments, alongside a column with the text “missing” as a submission status).