Author of the wiki here, I think GitBook is quite usable on mobile for me. What is the issue?
(Not OP) For me on Android Firefox the topic menu takes up the whole screen, doesn't scroll, and doesn't hide. On Chrome it seems to work.
Happens to me too =/
Firefox on Android.
OP here — works for me on mobile Safari
2021 and developers are still responding to support issues with "works on my machine!"
Ha ha! I'm not a dev any more, but old habits die hard, I guess. My comment was, in fact, to confirm for anyone who wanted to access with mobile Safari but who hadn't yet, that it indeed would work fine.