Excellent question. You can change the font sizes in the site. Go to the Appearance section in your WordPress dashboard. Click on theme options, then select the Content tab. The “body font” option there will change your paragraph, list item and many other “default” elements in the theme.
To change your headings, go to the Advanced tab and scroll down to the Custom CSS box. In it add this:
I took a quick look this morning, but I did not see the code in the Custom CSS on your site. Did you happen to clear out the W3 Total Cache’s cache after making the changes? That might keep them from showing up. Let me know what you turn up.
Glad that font size is working for you now. In the Content tab of the theme options page there is a drop down that will let you set a font for the headings. You can also change the snippets above to be like this: