1.4.1 Use of Color
Information and user interface components must be presentable to users in ways they can perceive.
Make it easier for users to see and hear content including separating foreground from background.
Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.
Note 1: This success criterion addresses color perception specifically. Other forms of perception are covered in 1.3 including programmatic access to color and other visual presentation coding.