Internet Explorer CSS: Can You Hack It?
Many web developers' lives have been complicated by developing websites that have to work with the limitations of older Internet Explorer browsers. If you use some slick CSS hacks, you can work around the limitations and "features" of IE and make a better website in the process--but are the hacks "safe"?
Mathias Bynens is an expert on the issue, and has created a breakdown of the methodology of dealing with IE's website rendering issues, including conditional stylesheets, classnames and CSS hacks. His site is called In defense of CSS hacks, appropriately enough.
He notes what he refers to as "safe" CSS hacks--those which "work in specific versions of a given web browser, unlikely to be parsed by all other browsers, including future versions." Sounds safe to me, and well worth looking into.