Can you slant, say, the bottom edge of a DIV?

Question

I have a design in mind that would require the header DIV to have the bottom edge not be straight, but angling up to the right a bit. I found a website that has an angled red box at the top, it spans the full width of the browser no matter the width, and adjusts itself on the fly. So it's clearly no graphic.
I've been googling for an hour, and can't find any reference to this type of technique. The sight I'm using as a reference is www.hotmeteor.com.
I've found how do angle corners of a DIV, but not a side of the DIV.
I'm thinking maybe the whole div is rotated and it's just going off the edge of the page?
Any CSS gurus out there?

Answer 1

Divisions are basic rectangles. As far as I know, there is no reliable way of altering their shape other than CSS transform:rotate which doesn't work in pre-IE9 browsers. 
http://alt-web.com/DEMOS/CSS-transform-rotate-on-post-it.shtml
Your example uses a Responsive Layout -- % widths for different devices. 
This CSS rule governs how images & objects are resized in different viewports.
img, object, embed {
    max-width: 100%;
Nancy O.