Cannot change size and form of menu

Hello,

I love this theme but I am having a slight problem with the menu. No matter what I do in css with either the primary menu or the portfolio menu, I cannot change the font size, nor can I add a box around the primary menu. It seems that no matter what I put in the menu css that it doesn’t register on the actual site. I know I am using the right css because other changes I make on the site show up just fine, it is only the menus that give me this problem. Any help at all would be appreciated.

Thanks!