I don't really know the answer to this question, but I bet you could sort of figure it out buy looking at both the HTML and the CSS stuff. AFAIK any text with its size defined in px will not change when you change the browser font size, but stuff with sizes defined in a different way will change. Also AFAIK, most text sizes in this board are defined using px, but I remember a time a few months ago where it seemed half and half, which made stuff look really weird if you changed the browser font size. I dunno if there is some sloppiness with different text being sized in different ways, but it seems like this would be the cause of the problem. I vote using px all the way, because then the size will be constant, only dependent on the screen resolution.
I have noticed that when things are sized not using px that they will look odd on Linux, cuz it sizes things differently than other stuff... but a pixel is a pixel, no matter what OS you use.
There was actually a huge discussion/argument that subBlue was a part of, deciding how the text sizes should be done. It seems like everyone desired a different way for this to work, from size=+1 or +2 style, to using "em", to using "pt" and everything in between. I hope that it is all done with px now, but I am not sure.
PS weird, I just tried changing the text size in the browser, and it appeared that no text sizes changed for me (using IE6), but it changed some of the line spacing for some reason.
PPS this post is rambling/running long, so I will put this request in here, and in a new post following this, so in case this post gets skimmed over, subBlue will catch it.
to subBlue: Is all of the text in the subSilver template sized using a certain technique? If so, what technique is that? Also, how does this affect the way that things appear using: different browsers, different text sizes within the browser, and different OS's?