Fix for hidden h1 headers when using links with anchor ids

Commit 173744c was added so I can direct link someone to the following and not have the header hidden by the top nav bar:
* http://angularjs.org/#the-basics
* http://angularjs.org/#add-some-control
* http://angularjs.org/#wire-up-a-backend
* http://angularjs.org/#create-components
* http://angularjs.org/#embed-and-inject

Commit 14f716b was because I thought that I was going to have to add more styles to .hero-unit to compensate for .navbar-fixe-top but ended up not having to. It is not necessary for PR but good CSS practice anyways.