I am rapidly improving the site right now, at least it looks like that to me. From the outside, it probably gives the impression that I’m making a mess of things. I managed to plug the great navigation presented by Guillaume Marty on NetTut+ into the german version of the site, and will work on the english part today. A lot still remains to be done, but slowly am inclined to call what I have assembled here of bits and pieces a flatfile CMS. In any case I think the site will improve visibly in the next days.
Edit April 25th, 2021: Link to Tutorial at http://net.tutsplus.com/tutorials/html-css-techniques/how-to-build-a-kick-butt-css3-mega-drop-down-menu/ no longer working.