Implement dark mode #210

Job	Run time
build-prod (windows-latest)	2m 32s
shellcheck	7s
tests (ubuntu-latest)	1m 39s
typecheck (windows-latest)	2m 10s
licence-check (windows-latest)	1m 47s
alex (ubuntu-latest)	26s
lint (windows-latest)	1m 43s
tests (windows-latest)	1m 52s
alex (windows-latest)	1m 45s
typecheck (ubuntu-latest)	42s
yarn-lock (ubuntu-latest)	25s
lint (ubuntu-latest)	48s
licence-check (ubuntu-latest)	30s
build-prod (ubuntu-latest)	58s
yarn-lock (windows-latest)	1m 56s
	19m 20s

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