WCAG success criterion: "Every keyboard-operated user interface has a mode of operation in which the keyboard focus is visible. People who access web applications with the keyboard should be able to recognize which element has been accessed with the keyboard focus. For this purpose the focus must be clearly marked.

Some elements are not highlighted clearly enough when focus is maintained, because the contrast of the corresponding marking to the non-focused state is too low (examples marked in red). The minimum requirement of 3:1 is therefore not met, which makes orientation more difficult for motor-impaired users.

This problem also applies to similar elements on the pages "Groupware - Calendar" pages.

On the checked page, focus retention is not visible on the controls marked in red. For motor-impaired users who navigate via keyboard, the focus tracking is therefore not possible. The keyboard focus should be clearly should be clearly visible regardless of the browser used.