Control width

I have just started using this module an I love it!

I have a question concerning the width of the dropdown boxes, though:

When used as a block, the box can get very wide. In my case too wide for the theme. Furthermore the boxes all get different widths so when you use several filters in one block it doesn't look that nice any more.

I have tried using css to control the width but is seems that I cannot influence elements.style via css. So i was wondering if there is any way to control the width of the dropdown boxes (to e.g. give them standard size). I tried searching the js file but I have no clue about this to be honest :(

Thanks a lot in advance!