[TYPO3-dev] Changing BE styles

[Joel Peterson]

I have two similar sites each with their own installation of Typo3.   What
is the easiest way to modify the look of one of the backends so as to create
a visual differentiation between the two?   I have tried extensions that add
CSS files to the backend but the edits don't appear.  I have even tried
modifying the xtheme-t3skin.css...   but nothing seems to "stick".  The
edits I made are not coming through.   I deleted the cache and removed the
files from the compressor folder as well with no success.   This seems like
it should be easy..  am I missing something?

Thanks very much,