Change the Font of the Top-Menu
If you would like to change the font size (or the weight, or font type) of the top menu of the navbar, use this. Note that this only effects the top-level menu only; it does not effect the sub-menu bar that comes out or down for the links within a folder.
Add the following code to your theme's Advanced CSS settings:
/* Change the font size of the top menu */
font-size: 20px !important;