This page tests out the interplay between HTML 4 headings, h1-6 and the new HTML 5 section element, which magically readjusts the "level" of any heading contained within it, according to how many nested sections (or articles) it;s inside.

You can check visually using the HTML 5 outliner tool.

I'm a top level heading (marked up as h1)

I'm a second level heading (marked up as h2)

I'm a third level heading (marked up as h3)

I'm a fourth level heading (marked up as h4)

Open first section:

I'm an h1 in level 1 section (so like an h2)

I'm an h2 in level 1 section (so like an h3)

Open second section:

I'm an h1 in level 2 section (so like an h3)

I'm an h2 in level 2 section (so like an h4)

I'm in second section

I'm in first section

I'm not even in a section! How keerrrrazeee is that?!?!