Over the weekend and today I've got the transformation working so that it now builds a completely updated version of the XML which complies with the current P5 (and some upcoming changes/deprecations), as well as abstracting all the styles into rendition elements. I've build an Ant build file which generates all this stuff automatically from the original XML, and then uses that to start building the web output. That means I can focus on website generation work without having to update the existing site code to take account of changes in XML, which is a relief. I'm building this so that it will run outside of Oxygen, in anticipation of its running on a build server we plan for HCMC.
I now have primary source text documents rendering, although in many cases the results are not pretty. There are some fixes to be made to the original documents, I think. We may also decide on putting menus at the top rather than down the side, which will involve some tweaks (but not much, really, because the new layout is designed to detach the site structure from the document display as much as possible). Tested the build on the laptop and it works great.