[Docs] Navigation responsiveness issues on tablet/mobile

[Andreyco]

In current state, docs navigation on touch devices (or small screens) is anything but ideal. Actually, it could be improved for larger screens as well.
Working on PR

[Andreyco]

Early version, basically proof of concept

[Andreyco]

Got it working nicely on handheld devices. Submitting code soon, see attached GIF.

iPhone

iPad

[Andreyco]

cc @vjeux @damusnet any thoughts on this?

[damusnet]

It does look nicer :)

[vjeux]

Omg, this looks so good! I'd definitively love to get this in. If you send the pull request I'll review it and get it merged. Please cc me (otherwise I'll probably not see it).