This is all @featheredtoast’s work 
We’re experimenting with the slide-in menus on mobile here on Meta and that will be merged in core at some point in the future so there’s not much you need to do but wait 
you can follow the progress here
This is all @featheredtoast’s work
We’re experimenting with the slide-in menus on mobile here on Meta and that will be merged in core at some point in the future so there’s not much you need to do but wait
you can follow the progress here