WPF .net4 webBrowser and Internet Explorer 8

Question

I have a WPF .net4 app with a webBrowser component that navigates to a local HTML page that uses a CSS file.

When I navigate to the page using IE8 the CSS styling is

Answer 1

The best explanation that I have heard for this behavior is that the webbrowser control is running in some form of 'compatability' mode.