H1-H6 font sizes in HTML

Question

In HTML (and in typography in general, I suppose), there appears to be some defined sizes for H1-H6 -elements.

Ie., if the baseline font size is 16px (or 100%), then h1

Answer 1

W3C suggested a default rendering stylesheet for browsers to implement.

You'll notice that your figures differ from them. That's because browser makers have a habit of ignoring everything W3C say.