What fresh hell is THIS now? - Patrick Lauke
aria-haspopup="true"
for the menu toggle.
[scottohara] here’s a piece i wrote about that: http://www.scottohara.me/blog/2016/08/10/not-really-about-the-button.html
but to summarize, if your nav landmark is hidden behind a hamburger menu (on large or small screen) then it will be invisible to assistive technology.
if you keep the nav landmark unhidden, and put the menu button within it / hide a sub-container of the navigation, then the nav landmark will stay discoverable to users, even if a nav is hidden