Replace divs with proper html5 landmarks. div.header -> header.header (class kept for css) div.subnav -> nav.subnav div.footer -> footer.footer Also since there are now two navs (primary on the left and the subnav with prev/next/index), all nav's get an aria-label to distinguish the subnav from the main nav.

@rem python -m pip install sphinx

python -m sphinx . html