For instance.. IE6 had a difference in the way it adds margins and widths for a long time - it's a bug (at least a deviation from the standards), some people relied on it.. but the common workaround is to not assign margins to the same elements as you added widths on. (and there are other methods, like display:inline coupled with floating..etc)

The point being.. that workaround doesn't break on newer versions - it simply avoids stepping on those stones.