Changing chat module width

I'm trying to include a skyscraper banner along side chat, but I cannot seem to narrow the module up enough to fit the banner on the page. I have managed to do with with another template, but UNI will not let me. I've tried the css files, and other files,but nothing works. Does anyone know where I can do this?

what chat do you mean ? (simple messenger, IM or video chat)

I'm sorry, I'm referring to the video chat. I need the whole chat, and module title bar all to be narrower, so I can add a skyscraper banner to the right of the chat, without stretching the page and adding a bottom scrollbar. Thanks for your help.