On using h1 for all heading levels in HTML5
One of the problems that HTML5 aims to solve is that of heading levels, particularly in documents where content is cut and pasted from other documents or inserted through syndication from another source. In previous versions of HTML you need to manually make sure that any headings in the inserted or copied content are of the right level, i.e. h1-h6.
You can keep using h1-h6 in HTML5, but you can also choose to use only h1 elements for all headings and rely on the HTML5 outline algorithm to sort out the heading hierarchy. If you do this, however, you should be aware that currently there is very little support for the HTML5 outline in web browsers, screen readers and developer tools.
I bring this up because I have seen some HTML5 articles and blog posts that mention the new document outline without emphasising the current lack of support. That lack of support is a problem because it makes headings less useful to people who need a proper document outline to better understand content structure and use them as an aid for navigating within web documents. The most common example is screen reader users.
If [...]