Managed to get the basic site pages ported over to Greg's design, with the accordion menu working. One limitation of the accordion menu emerged immediately: it always opens the first submenu, even if you've just landed on a page from the second one. I've had to write some JavaScript that decides which submenu to open by comparing the current path to a list of filenames from each submenu category. A bit hacky, but it works.

Next is integrating my original style-switching code (JS and Cocoon sitemap switching based on cookies) so that Greg's style submenu works.