Enter email ui fix 20240402

The "Enter Email" modal has changed its appearance:

I tried going back to previous versions and it still has this appearance in commits from over a month ago, though I never saw it look like this: I wonder whether Chrome's line-wrapping behaviour has changed? Anyway, I fixed it in this MR:

I also made a small refactor of the config manager UI layout: it had div elements inside span elements, which isn't supposed to be legal. The spans were displayed as blocks anyway, so I just changed them to divs. Also added a code comment.