[intranation]

Or... you could just use a Javascript framework that takes care of that abstraction for you. This is seriously not a hard problem.

[moe]

Well, frameworks go a long way but they don't help with the pains in the CSS area. When supporting IE6 you're generally limiting yourself to the capabilities of that browser. And for any non-trivial site you will run into hard problems regularly, unless you're leaving HTML behind entirely (ExtJS, Flash).