I'll make this short and bittersweet: Cascading stylesheets are great, Web browsers are not so great.

Internet Explorer 3.0 was the first browser to try to support stylesheets, and its attempt was valiant, particularly because at that point the official specification had yet to be solidified. As a result, IE 3 supports most of the CSS properties, albeit with some bugs.

You'd think that by the time IE 4 and Communicator 4 came out, stylesheets support would be rock-solid in both of them. Well, it wasn't. It looks like the development teams at Microsoft and Netscape each had their own interpretations of some of the CSS properties, and other properties weren't supported at all. The result? Designing a CSS-riddled site for older browsers can feel like walking in a mine field. Most things work but some don't. And even when things seem to work fine, you'll find they appear differently depending upon the browser.

Luckily, over 75 percent of Web users surf the Web with IE 5, which is a bit kinder with CSS - but it's still not 100 percent. Betas of IE 6 and Netscape 6 are much more promising, but relatively few people use them.

Our Browser Chart gives you a general idea of which browsers support what. But for the details, you'll have to test as you go. When using stylesheets code, it's essential to test your end product on multiple browsers and multiple platforms. This is the only way to avoid unpleasant surprises. And when you find that your razzle-dazzle, stylesheeting-action site doesn't work on older browsers, you'll have to concoct a tamer version of the site to serve up for those old-school users.

That about wraps it up for Lesson 1. Now let's review.