Refine account UI

Current account UI looks... ugly. Especially on small screens: on my laptop it even doesn't fit at whole screen at height and I unable to edit some options.

This MR slightly refine account UI by positioning smtp & imap settings side-by-side instead of column. See some screenshots:

Welcome screen before:

And after:

Same for edit screen:

vs

Please feel free to talk about other changes if it required.