fixes #6333 - CSS float right for Admin Menu is not right justified on some browsers

Since the contents are float right, the height is essentially ignored. By adding padding, the div now has a "height". This fix is not needed on Chrome browsers, but there is an issue on some Mozilla browsers.

Note, the minimum for the fix was `padding-bottom:22px`. I added an extra 3px so that the gravatar isn't touching the bottom border line. Is this is desired, then I can change from 25px to 22px.