Ultimate Facebook Comments: different width?

Hello,

how can I apply different sizes for the Facebook Comments box? My pages are in a 2 column layout, my posts in a 3 column layout. And I want people to be able to write comments on both... In the settings of Ultimate Facebook I can only enter one single width in pixels for the Facebook Comments box. So it always only looks good in one layout... Any ideas?
Thanks in advance,
Eike