I agree it's a single-page application, but while you are navigating content appears to be loaded just ahead of time. E.g. pop open some of the menus, then whil

I agree it's a single-page application, but while you are navigating content appears to be loaded just ahead of time. E.g. pop open some of the menus, then while you're thinking what to click, they appear to load the different pages that you can navigate to from that menu. They don't load the rendered pages, rather their content as "data", which the single-page application knows how to render.