Are H1,H2,H3,H4 tags block or inline elements?

Question

Is it correct HTML to change the color of text inside a H1, H2, H3 or H4 element? Are they block level?

For example

Answer 1

Yes, a span within a h1 tag is allowed. As you can see on the W3C Reference page for the h1 tag:

Permitted contents: phrasing content

And phrasing content is normal text as well as your span element (and several other elements as can be seen on this reference page for phrasing content.

Oh yeah, and the heading tags are block elements.