Is the Mini a G4 or Intel processor? Doing "About this Mac" from your Apple menu will show the processor type. I'm finding many sites that do not properly support G4 processors. As Apple abandoned that technology about 7 years ago, web developers seem to have no problem ignoring the G4
If you Mini has an Intel processor, please post the version of the Mac OS you sre running on it (it is also in the "About this Mac" window) and we can go from there.