I have a solution that I use only when I have to, after I build my html & css valid and working in most browsers, I do the occasional hack with this amazing piece of javascript from Rafael Lima. http://rafael.adm.br/css_browser_selector/
It keeps my CSS & HTML valid and clean, I know it's not the ideal solution, using javascript to fix hacks, but as long as your code is originally as close as possible (silly IE just breaks things sometimes) then moving something a few px with javascript isn't as big of a deal as some people think. Plus for time/cost reasons is a quick & easy fix.