Change menu font

Heeeellllllppppppp

I’ve read the other posts on changing the menu font and size but I just can’t seem to locate where to do it.
I keep seeing comment on base.css file (which I can’t locate) and I do see base.css when I “inspect element” on my webpage, but for the life of me I just can’t figure this out.

Can someone please try to help me?

http://www.charlestonsocialtimes.com