Raindrops: How to increase font of header text on banner image?

Hi, I am using raindrops version 1.127 and would like to increase the font of the header text on the site banner image.
To make the header a little lighter I removed the top banner (as per http://wordpress.org/support/topic/remove-top-banner?replies=6) just leaving the image with site-description info on top.
I would like to have my sitename displayed over the image, which a larger font. Any hints on where to change this?

Site: http://www.tomcroes.com

Thanks,
AC