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

The easiest way to find out whether an element is block level or inline element is to put a border around it.

HTML

 Heading 1 
 Span 

CSS

h1 {
   border: 2px solid green;

}

span {
   border: 2px solid blue;
}

More examples on jsFiddle.