PUBLIC MARKS with tags support & browser

"You may well ask: “How can I start using HTML5 if older browsers don’t support it?” But the question itself is misleading. HTML5 is not one big thing; it is a collection of individual features. So you can’t detect “HTML5 support,” because that doesn’t make any sense. But you can detect support for individual features, like canvas, video, or geolocation."

Démonstration et comparatif du support des fonctionnalités HTML5.

Spec sur le support CSS par Opera 9.