Seems that new browsers support most of the tags: <header>
, <section>
etc. For older browsers (IE, Fx2, Camino etc) then you can use this to allow styling of these tags:
document.createElement('header');
Would make these older browsers allow CSS styling of a header tag, instead of just ignoring it.
This means that you can now use the new tags without any loss of functionality, which is a good start!