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The contrast ratio must be at least 4:5 against the background and 3:1 against adjacent colors.
Color Should Not Be Used as The Only Way to Convey Information
Ensure that all sighted users can access information that is conveyed by color differences, that is, by the use of color where each color has a meaning assigned to it.
If the information is conveyed through color differences in an image (or other non-text format), the color may not be seen by users with color deficiencies. In this case, providing the information conveyed with color through another visual means ensures users who cannot see color can still perceive the information.
Color is an important asset in design of Web content, enhancing its aesthetic appeal, its usability, and its accessibility. However, some users have difficulty perceiving color.
People with partial sight often experience limited color vision, and many older users do not see color well. In addition, people using limited-color or monochrome displays and browsers will be unable to access information that is presented only in color.
This benefits:
Users with partial sight often experience limited color vision.
Some older users may not be able to see color well.
Users who have color-blindness benefit when information conveyed by color is available in other visual ways.
People using limited color monochrome displays may be unable to access color-dependent information.
Users who have problems distinguishing between colors can look or listen for text cues.
Please see more detailed information on how to comply with this guideline.
WCAG Related References
1.3.3 Sensory Characteristics (Level A)
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