How to get rid of the focus rectangle?

[Leo Savernik]

Hello,

Whenever a node receives the focus, it gets a focus rectangle painted around. 
I first suspected a

:focus { outline: dotted 1px invert; }

rule somewhere in html.css, but there is none.

When I tried to switch it off by inserting

:focus { outline: none }
a:focus { outline: dotted 1px invert; }

into html.css (so that links would retain the focus rectangle), it didn't take 
effect. Outlines are still applied to every element that receives focus, not 
only to links.

Interestingly, when I put the above rules into an author style sheet, they 
work as expected.

Could anybody give me a hint where to look for the problem. I tried myself but 
haven't been successful so far.

mfg
	Leo