Converts most if not all screen to matching dark theme screens.
Please note that some windows, like right-click window, are set by your GTK theming (this counts for any FireFox theme, as themes can't alter them currently). Theme is set as a dark theme, so as long as there is an option for a dark (GTK) theme on your OS everything will be dark-themed. However, some windows might not match the this specific theme perfectly depending on your GTK theme.
