Browser Dark Mode (Chrome and Firefox)
       Dark Mode luckily has become a thing also in the non-unix world. Finally
       browser can be used with dark interfaces and websites can have
       alternative color schemes.
       However, in other operating systems, there is a global toggle for dark
       mode, which also switches the browser into it. This is not the case on 
       linux and unix systems.
       Chrome and Chromium starting with version 73 can be tought to start in 
       dark mode:
           $ chrome --enable-features=WebUIDarkMode --force-dark-mode
       Then go to chrome://settings/?search=themes and switch the theme to 
       Firefox got the dark mode in release 70.
           0. Go to "about:config"
           1. Enter "ui.systemUsesDarkTheme" into the search bar
           2. Click "Number" and then "+"
           3. Enter "1" and click the check mark
       Right click on a free spot in the icon bar and select "customize". At 
       the bottom left of the screen, you can switch to a dark theme.
       Note: If you've set privacy.resistFingerprinting to "true" the CSS dark 
       mode switching won't work. Kudus to for figuring 
       this out.
       There you go, both browsers are in dark mode now. The UI should be dark
       and also websites that support the @media (prefers-color-scheme: dark)
       directive should make use of it.
       You can test it on my webpage ( The light version
       has a light gray background and a blue font. The dark version has a dark
       gray background and an orange font.
       # Changelog:
       # * 2020-05-17: Created