The contrast ratio between the foreground color and the background color needs to be kept as low as 4.5:1. If the foreground color and background color are not distinctly different, you should pay attention. For delicate parts, measure the contrast ratio. In particular, pay attention to main content and menus.
Among the check items, it is said that it is only necessary for the web page side to provide a mechanism to change the contrast, but users with weak sight also have black and white reversal at the OS level in the first place, and ideal is enough It will ensure contrast.
For color vision deficiencies, consideration is given to specific color combinations. It should be noted that red and green, orange and yellow green, green and brown, blue and purple, pink and white or gray, green and gray black, red and black, pink and blue.
| Principle | Perceivable | Information and user interface components must be presentable to users in ways they can perceive. |
|---|---|---|
| Guideline | Distinguishable | Make it easier for users to see and hear content including separating foreground from background. |
| Criterion | Contrast (Minimum) (1.4.3 AA) |
There is a contrast ratio of at least 4.5: 1 for visual presentation of text and character images. |