Add popover, fix mastodon domain processing, tweak styling #116

Job	Run time
check / install (ubuntu-latest, 20.x)	49s
check / lint-and-test (ubuntu-latest, 20.x)	1m 33s
Build video / build-push	8s
Build push / build-push	1m 0s
Build server / build-server	1m 9s
	4m 39s

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