Make sure to enable Contrast within Sa11y's settings.
jQuery contrast plugin was created by jasonday. To prevent false positives, a simple condition was added to exclude any elements whose width and height is less than 1px and contains overflow:hidden;. Some contrast plugins falsely indicate visually hidden text for screenreaders as a contrast fail.
Tooltips will indicate whether it's large or normal size text, including the snippet of text that fails.
Example 1 - Normal text
This colour fails at normal size.
Example 2 - Large text
This colour also fails at a large size.
Example 3 - Form input
Input's text color is too low.
Example 4 - Warning
Warnings for text that uses CSS backgrounds.