Uneven focus ring

[gaearon]

This was introduced by #53.

You can only see the unevenness when the tree is small enough to fit on a single screen:

I think we can just hide that focus ring altogether, and instead either show a custom one in the right area (e.g. via focus events), or not show it altogether (somewhat worse).

An ideal version would be to show it in the right place and only if you navigated into the area by tabbing.

[bvaughn]

This has to do with overflow/clipping. Before I added custom :focus styles to e.g. the owners list, those buttons had the same problem. I'd be happy to pick this up if you'd like a hand. (Not going to touch it for the moment though, since you've self assigned it.)

[gaearon]

If you don’t mind doing it that would be great! I’m going to focus on the suspense fragment thing.

[bvaughn]

Fixed via d1a5346. Also addressed a couple of other minor keyboard navigation UX issues I noticed while testing.