Excelent open source addon. Followed suggestions from https://github.com/m-khvoinitsky/dark-background-light-text-extension/issues/222 and tweaked global color from hard dark to softer:

Default foreground color: #B0B0B0
Default background color: #303030
Default link color: #7777ee
Default visited link color: #663e8b
Default active link color: #A03333
Default selection color: #ffd38c

Worked great!

Finally, a dark theme that's actually beautiful and works very well. Truly a masterpiece.

A great app that doesn't take up to many resources. I also really liked Midnight Lizard but it was to heavy on resources (even with a 7th gen i7 + GTX1060 running arch) so I will stick to this one. This add-on is one of the easiest to configure while providing enough customization settings to make the theme your own. I use it in combination with WaspLine Reader to make the text easier to be read (I'm dyslexic) and it supersized me how nice the text renders, because I had trouble using wasp with other dark mode extensions.

The only dark mode extension that doesn't completely F*** my ram usage

I use it since years and I really love it. Websites should always look like what this addon makes 'em look like!

Edit (2021.03): I really encourage the developer to bring a version for Firefox Android/mobile. Please do this favor to your users and "want-to-users".

Right now I'm using dark reader (https://addons.mozilla.org/en-US/firefox/addon/darkreader/) for this purpose. But It just isn't as good, versatile and easy to use for every website as "Dark Background and Light Text" is. It simply doesn't work on lots of sites or breaks the sites. So you have to fiddle around till it somehow halfly works (often if nothing other works you have to use the static mode. Which only makes the background dark but ignores your text colour settings, and makes the text white).