When a user interface component receives keyboard focus, the component is not entirely hidden due to author-created content.
Ensure when an item gets keyboard focus, it is at least partially visible.
People who can’t use a mouse need to see what has keyboard focus.
Having a modal positioned on the page so that it covers part of the content. If focus handling is not done correctly, it is possible that some interactive element is behind the modal and the focus style of it cannot be seen.
Check the page and ensure that no element completely covers the interactive elements on the site.