Individuals with visual disabilities have difficulty seeing content that does not create a significant contrast with its background. Blind users are not able to notice different colors used on a web page.
Any colors chosen for text, icons, or other symbols should contrast greatly with the background. Color should not be used as the sole means of representing information.
Avoid referring to colors, sizes, shapes, and other physical traits as the only method of description. For example, don't say "Click the big, round, blue button," since users with visual disabilities will not be able to discern which button this refers to.
These measures allow individuals with visual disabilities to understand content presented visually, as well as users of assistive technology to interpret information communicated via the use of color.