[Plugin: font-resizer] Only changes Navigation fonts not body in Headway Theme

This may be a Headway issue but I’ve tried two different font resizers and they both work with the default WP theme but not Headway. They only change the font size in the Navigation instead of the body. Is there some CSS or code I can use to make this target the correct content? Thanks.

http://wordpress.org/extend/plugins/font-resizer/

UPDATE: I just discovered that the default in Headway is for font size to be defined in px and not %. Hence, font resize plug-ins won’t work. Not sure if I can make the entire them into % in order to use it but I’ll try.