Move css from body to .content

In order for the header to expand the whole length, I need a .content
div for the rest.
h1 title for article, h2 for comments
Add header css

## HTML
* Extra div for background
* <header> to wrap content. <nav> is allowed in <header>
* <hgroup> for title + subtitle.
* <h1> for site title. On article pages this will lead to two <h1>
which is ok for SEO, because it is not missued.
* <nav>

## CSS
* Fixed
* Semi-transparent
* hgroup float:left
* nav float:right
Indent .index css