height:100% combined with position:fixed pushes some off the content off
the edge of the window. Also, the splitter doesn't work in Redmine
embedded, so it's better to not display it at all.
apigen.css was taken from ApiGen's default style.css with 3 changes:
1. All images are inlined as data URIs
2. All styles are restricted to #content
3. The search bar, which doesn't work with Redmine embedded, is hidden