Well, thanks should go first to Olle Axelsson, who created the design originally. I liked it a lot too and figured it would be a nice addition for TikiWiki. I'm looking at a couple more of his themes for Tiki versions also.
In the back of my mind, the font size in IE was bothering me, too (the kind of thing that needs to be dealt with but gets put off). I increased it a bit and uploaded the changed eatlon.css to Tiki's Subversion repository. You can get it here (save as eatlon.css and upload to your Tiki's styles directory). New downloads of the Eatlon theme will have this revised version.
FYI, the font size is set in the stylesheet, for the body tag that controls the page overall (a property of 74% or so), and again in a few places for specific page parts - the #tiki-center div is 1.1em, to increase the size in the center column, for example. Most font sizes in my themes are set like this, with an overall-page percentage (because browser defaults are rather huge) and then ems or percentages within the page. In a few places there's a size in pixels for IE6 as it doesn't handle cascading of font sizes well (forgetting parent sizes when setting sizes of text in child objects, etc.).