Title: Enable dark mode on Firefox

	Title: Enable dark mode on Firefox
	Author: Solène
	Date: 04 May 2020
	Tags: firefox
	Description:

	Some websites (like this one) now offers two differents themes: light
	and dark.

	Dark themes are proven to be better for the eyes and reduce battery
	usage on
	mobiles devices because it requires less light to be displayed hence it
	requires less energy to display. The gain is optimal on OLED devices
	but it
	also works on classic LCD screens.

	While on Windows and MacOS there is a global setting for the user
	interface in
	which you choose if your system is in light or dark mode, with that
	setting
	being used by lot of applications supporting dark/light themes, on
	Linux and
	BSDs (and others) operating systems there is no such settings and your
	web
	browser will keep displaying the light theme all the time.

	Hopefully, it can be fixed in firefox as [as explained in the
	documentation](https://developer.mozilla.org/en-US/docs/Web/CSS/@media/
	prefers-color-scheme).

	To make it short, in the about:config special Firefox page, one can
	create a
	new key `ui.systemUsesDarkTheme` with a number value of `1`, the
	firefox
	about:config page should turn dark immediately and then Firefox will
	try to use
	dark themes when they are available.

	You should note that as explained in the mozilla documentation, if you
	have the
	key `privacy.resistFingerprinting` set to `true` the dark mode can't be
	used.
	It seems dark mode and privacy can't belong together for some reasons.

	Many thanks to
	[https://tilde.zone/@andinus](https://tilde.zone/@andinus) who
	pointed me this out after I overlooked that page and searched a long
	time with
	no result how to make Firefox display website using the dark theme.