Heading and excerpts get pregrssively smaller on blog homepage

Hi again!

I've noticed these problems for a couple of our users who have applied themes from the 100 Theme Pack - Freshy and Regulus

You can see examples of the problems here:
- http://boroblog.futd.com/
- http://thegroundhog.futd.com/

Basically for the user who is using the Freshy theme, when you scroll down his homepage the headings and excerpts get prgessively smaller and smaller!

Similarly, for the user using Regulus, the headings only get progressively smaller and smaller...

Any ideas what I need to tweak to get the themes to stop doing it? It's an unusual but partcuarly irritating problem!

Sam