Re: [WebAIM] Contrast and Color Accessibility, Understanding WCAG 2 Contrast and Color Requirements

Also worth looking at the updates I’m proposing:

For 1.4.11:
·         Components must continue to have contrast in different states ("required to identify").

·         Where a state indicates functionality of the component (e.g. a check in a checkbox), that aspect must have sufficient contrast ("required to identify … states").
However, it does not create a requirement to differentiate states by color internally (e.g. between default and hover, visited link, visited + hover etc.).
(A better term than "functionality" would be useful there.)

In combination with Focus Visible (2.4.7) & Use of Color (1.4.1)
·         if the focus indicator relies on color alone (so all three SCs!), that must provide contrast compared to the non-focused state. (E.g. changing the background color of a button.)

·         if the focus indicator adds/removes parts of the component, or changes the shape of the component, that change must have contrast. (e.g. adding thickness to a border that has contrast, or adding a separate outline.) However, it doesn't have to contrast with itself if it changes the shape.

Not in scope:
·         Boundaries for links / buttons.
·         Default (untouched) focus indicators.
·         Measurement is against adjacent colors of the component, not different states within the component (except when color-change-only is used for focus state).
·         Hover / visited state (except that the component must continue to have contrast). Whilst desirable that a component would indicate hover state in a perceivable way, it is not required by 1.4.11.