Font size adjustable?

In practice is the font-size adjustable when using JQueryUI?
I ask this because it seems all widgets are designed with a very small
font size in mind. For example, the icons supplied with JQueryUI may
not be usable with larger fonts because they will appear
disproportionately small.
Are there any webpage examples were people use JQueryUI and a larger
font-size?
Thank you for your help, Kevin
--