I am looking for a 100% CSS way to have a full page image on a site.
That expands/contracts as the window is re-sized.
Like this one: http://ringvemedia.com/
But I need a 100px empty space at the top for a header.
I specifically do not want the full page image to hide behind the header.
I want the top of the image to start at the bottom of the header, not creep up behind it.
You mean like this? Just marked up some quick stuff — Overlay is optional to defeat harsh background color with content over top (unless you fill a div with white space)