Font size

I am new to WordPress. My company runs a blog and as we had a lot of categories I wanted to introduce child categories that were only revealed when clicking on the parent. I downloaded the folding category widget that solved this but the font size was too small. When I try and change it on Firebug I can change all my other widgets size independently but the folding category one always has to be the same size as the rest of the body. Anyway how can I stop this from happening? Thanks in advance