Getting html5 pages right is important, along with flexibility comes some responsibility… good tutorial
HTML5 introduces the concept of relatively ranked headings. The level of a heading in HTML5 depends on its location within one (or more) sectioning elements – specifically the<nav>, <section>, <article> and <aside> tags. The HTML5 outlining algorithm makes it possible to use only <h1> headings on a page. The level of the heading is then redefined based on the nesting of the sectioning elements it’s wrapped in.