Hi Aaron,
Sorry you are having difficulty styling your favorite theme.
To see ANY changes you make to the CSS (or any other file in your chosen theme in Moodle 2.0) you first need to ENABLE Designer Mode, which you will find in Site Administrator > Appearance > Themes > Theme Settings... Put a TICK in the box next to Designer Mode then save your settings and go back to your HOME page. Then REFRESH the browser (Ctrl+F5) and you should see the changes you have made to the font size.
The way the FONTS work now in Moodle 2.0 is enhanced by some EXTRA css from YUI Library. It can sometimes over-ride custom settings. If you find that the font is still not the size you want after making changes to the CSS in the Formal White style-sheet, try adding !important just after the 1.2em.
Mary