Note:We talked about some of these ideas in our Winging It live stream last month with Alan Stearns, co-chair of the CSS Working Group. Check that out for more discussion of typography and CSS units! The browser provides a default text size based on user preferences, and our text should be relative to that preference. Establishing our root font-size with an em value helps keep that relationship intact. Similarly, font ‘scales’ are intended to maintain some internal harmony across a range of diff...