Add popover, fix mastodon domain processing, tweak styling #256

Job	Run time
check / install (ubuntu-latest, 20.x)	29s
check / lint-and-test (ubuntu-latest, 20.x)	1m 20s
Build video / build-push	17s
Build server / build-server	1m 11s
Build push / build-push	1m 2s
	4m 19s

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