Cross browser differences

As a designer I am often frustrated with the differences between browsers. Obviously, there are ways around these differences (such as using browser specific stylesheets) but this adds unnecessary time.

When will the day come when you can create a design and not have to plough through the many browsers and platforms to ensure it is pixel perfect all the time. I use Firefox now on a PC and have done for some time (due to the way it renders pages and also the fact there are hundreds of useful plug-ins about for designers / developers) and I find it much easier to create a design and test in FF and then fix all the discrepancies in other browsers at the end.

Will the day ever come when all browsers will render pages the same? Probably not but it would make life easier and free up more time to work on designs. Also, why can't browsers on a PC render text as well as on an Mac. Designs always look so much nicer on a Mac.