Focus Not Obscured (Enhanced)
When a user interface component receives keyboard focus, no part of the component is hidden by author-created content.
In plain language
This is the strictest version of the focus-visibility rule: when something is focused with the keyboard, absolutely no part of it — not even a sliver — can be hidden behind other content.
Why it matters
The AA-level version of this rule only requires that focus not be completely hidden, meaning it could still be partly covered. This stricter version removes that gap entirely, so keyboard users always see the full focused element, with no ambiguity about what's selected.
In practice
Fails this criterion
A sticky footer covers the bottom few pixels of a focused button as the page scrolls, partially hiding it.
Meets this criterion
The page adds enough scroll space so that a sticky footer or header never overlaps any part of the currently focused element.
Test it yourself
Tab through the page and watch each focused element as you scroll near sticky headers, footers, or other overlays. If any part of the focused element — even a small sliver — gets covered, this criterion is failing.