Hgroup not working for me. Why?

I just got HTML5&CSS1 in the mail yesterday and I’ve already started. Immediately I ran into a small problem with the hgroup element. I did it exactly as described in the book, but my results doesn’t outline. Take a look at my code:
<header>
<hgroup>
<h1>The HTML5 Herald</h1>
<h2>Produced with that Good Ol’ Timey HTML5 &
CSS3</h2>
</hgroup>
<nav></nav>
</header>
This is what it looks like in the browser:
The HTML5 Herald
Produced with that Good Ol’ Timey HTML5 & CSS3

No outline! What am I not getting right? Please respond.

Apparently you are supposed to download some JavaScript called h5o to see that effect in the browser by the looks of things [p39].