Neither.
It is a problem with the way the web designers code their pages. I have a Mac and a PC and the very same graphic on the very same page will render differently.
You might also want to download
Safari Enhancer which unlocks some features of Safari and allows it to ID itself as IE or other browsers. It comes in handy for viewing some websites that do not like non-IE broswers.
I use Camino as my browser and their is a similar program called CamiTools that I use to do the same thing. Both work like a charm and I rarely run into a website that I cannot view.