Hmmm... well, I kinda like the current look! I can't really change the font size etc (well, I can but it's a bit too inflexible in that I change it and it changes all sorts of things, so it would take a bit of fiddling), and in any case what may suit you may not suit others. However...
You can change the look and feel for your own view of the forum. I only have two other options, but try them out. I may add some more at some later stage.
Go to PROFILE from the nav bar at the top. Then, choose Look and Layout Preferences in the MODIFY PROFILE section on the left. At the top of this next screen you'll see the words Current Theme: SMF Default Theme - Core (change).
Click the link (change).
On the next screen, click the Use This Theme link next to the Classic YaBB SE Theme. This theme is a bit more conservative and uses more easily read fonts. Once you've done this, click the HOME link in the nav bar.
That may be enough for your needs. Let me know what you think.
Graeme