I think this is a problem since Mac's use 72 pixels per inch by default and PC's use 96 pixels per inch. I believe there is a setting so you can adjust it.
Also, since you are still running OS 9, try iCab. It's a small but powerful little browser. It doesn't do javascript perfectly, but it renders most pages very well and is customizable.
http://www.icab.de/dl.php