Offcanvas is tricky to work with in Blocs at the moment. It is going to be very useful though for sure. @Norm is going to do something amazing here I hope
It is not at all clear from the @Eldar tutorial whether this method can be used in the body of the page, rather than as a menu item, set above the top line, which does not change.
What I am looking for is that kind of capability, but have it contain different material for each separate web page.