Different rendition of Track Title text

In the V2999a7 Default theme the Track Title text is defined as "Microsoft Sans Serif, 11pt" If I use those settings in my own theme the track titles (and track numbers) are much bigger. Have a look at these screenshots: Big pic: Can someone tell me what setting I have missed?

I've experienced similar font size weirdness, which I posted earlier here:

Hmm, over 100 views. 

I should say that this happens in v2.54 and earlier versions too. I raised it here because of the other problems with the track name text in these alpha versions. Windows XP Home SP2