Recently I've been on an XHTML binge, making sure that all of my pages validate. In line with this also means making heavy use of Cascading Style Sheets, which are very nice to use.
Unfortunately, when using Netscape 4.x, one needs to turn on Javascript to actually get Style Sheets enabled, even through it doesn't seem like you should. Irregardless, Netscape 4.x does not do a very good job of rendering many different types of CSS well. Mozilla and Internet Explorer, on the other hand, do seem to do an excellent job; for instance, take a look at my personal page with both Netscape 4.x and then Mozilla or IE. There is a noticeable improvement.