that’s just wrong: is not a wrapper. The element denotes a semantic section of your content to help construct a document outline. It should contain a heading. If you’re looking for a page wrapper element (for any flavour of HTML or XHTML), consider applying styles directly to the element as described by Kroc Camen. If you still need an additional element for styling, use a . As Dr Mike explains, div isn’t dead, and if there’s nothing else more appropriate, it’s probably where you really want to apply your CSS.
you can check this : http://html5doctor.com/avoiding-common-html5-mistakes/