3R - Specificity - A11Y

CSS Specificity: Specificity is somewhat of a score or rank that can determine which style declaration is applied to an element. If two or more CSS rules point to the same element, the one with the highest specificity value will be chosen and style declaration will be put into the HTML element. 4 categories define a specificity level of a selector that would be 1. Inline styles, 2. IDs, 3. Classes, pseudo-classes, attribute selectors, and 4 Elements and pseudo-elements.

Contrast Ratios: Contrast ratios measure between text and graphics against background colors. When designing a readable interface for different vision capabilities, it is recommended that you follow the WCAG guidelines for contrast ratios. Having good color contrast on your sites benefits for all users who comes across it, but mainly beneficial to users with certain types of color blindness or similar conditions who experience low contrast or differentiating colors. The design of your web page is worthless if users can not read the contents.

you must meet contrast ratios: Graphical components and text on web pages need a accessible contrast so that it is perceivable to other users. Some users have reduced vision and others wills be in situations where contrast is important

What Group at W3C sets accessibility rules: The WCAG technical documents are created by the Accessibility Guidelines Working Group (AG WG) Formerly the Web Content Accessability Working Group, which is apart of the World Wide Web Consortium (W3C) Web Accesibility Initiative (WAI)

Summary: Overall CSS Specificity and Contrast Ratios are essential to have at the right level due to users with certain disabilities, it makes it easier for them to read and understand your web page. It is also important for the developer as well because if they create a web page they want it to be accessible to all users and not just those with fine eye sight and no disabilities.