Visually highlight interface components when they receive focus
Make sure active elements are highlighted when they receive keyboard focus
Users who can’t use a mouse for whatever reason will often navigate through a page using their keyboard’s tabulation key, jumping from one active element to another (form controls, links and so on), based on source code order. Focus is generally displayed as a blinking vertical bar at the insertion point in text field, or as a dotted focus highlight rectangle on a link. This focus indicator needs to be easily noticeable, so progression through content can be effortlessly followed.
To do [...]