When the keyboard focus indicator is visible, an area of the focus indicator meets all the following:
- is at least as large as the area of a 2 CSS pixel thick perimeter of the unfocused component or sub-component, and
- has a contrast ratio of at least 3:1 between the same pixels in the focused and unfocused states.
Exceptions:
- The focus indicator is determined by the user agent and cannot be adjusted by the author, or
- The focus indicator and the indicator's background color are not modified by the author.
Use a focus indicator of sufficient size and contrast.
Many people can't see small changes in visual appearance, including older people.