I have Chrome, Firefox, IE8 and Opera installed, to properly test my site for compatibility.
Opera is the only one that seemed to have issues, but it wasn't so much that Opera had issues, rather my site had issues and Opera highlighted those issues so I was able to fix them.
The reason for "anomalies" between some browsers and not others, is pretty easy to explain.
Chrome and Firefox pretty much "copy" each other. That is, one of them will implement a W3C spec a certain way, and the other one will do it the same way; the specifications themselves are rather vague and open to interpretation, so other browsers that don't copy it might do things differently, but still be perfectly within the spec.
Basically, the reason that some browsers might have issues where others don't is typically because the website author has become dependent on the specific way that certain elements are handled by some browsers.