How to change Product Categories Font and size

I have looked for hours through the code as well as the various forums to find the right stylesheet and appropriate class to modify so that I can change the font and style of the product categories one sees in the widget area of my website: https://www.goodolddayscountryshop.com/WPstore.
Thought Firebug would point me right to it but cant figure out that beast either so after a half a day on just this simple little task, I figured it is time to call for help.
Can one of you please tell me which stylesheet contains this information?
Also, since these stylesheets do not have many comments in them, which member of the class is the product categories called?
Thank-you so much.
John