UX: adjust poll button spacing (PR #14230)

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The title of this pull request changed from “UX: adjust button spacing” to "UX: adjust poll button spacing

I really wish we could start avoiding this kind of things and favor a more general approach. Can you look at @pmusaraj PR ?

I think this is fine @jjaffeux, the PR I’m working on does not handle horizontal margins. (Plus it’s still a draft and I don’t expect we will merge it until at least next week.)