In medium to large viewports, we see a main menu (generic) and a sub-menu (site specific):  On small devices, the sub-menu disappears and its links aren't available anywhere:  And by clicking the hamburger menu, we see the mail menu only: 
In medium to large viewports, we see a main menu (generic) and a sub-menu (site specific):
On small devices, the sub-menu disappears and its links aren't available anywhere:
And by clicking the hamburger menu, we see the mail menu only: