I never write reviews for extensions but, for those suffering and or struggling with vision issues this extension is going to help you. I was running DarkReader and thought it was good - little buggy / wonky and broke a lot of things and caused frustration regarding always messing with parameters that never helped my vision. Sepia changes always riding the faders so-to-speak and then setting websites in memory "only for site x". Forget that.

Firefox background tweaks mess up the entire browser and skin the entire side panel (Sideberry) and blankets themes and mucks up the vision. Ditch that. That's never going to help those suffering with vision issues.

I stumbled upon Dark_Backround_Light_Text and in a matter of a seconds I discovered this is the tool I needed all along. I finally found an extension that's simple to use that doesn't muck up the browser skin, doesn't mess up the side-panel (Sideberry / Tree-Style-Tabs) theme that goes with the browser skin / theme and allows the background and font colour to be changed.

Example: Gmail online theme is no longer impacted. Just the text and background colour. There are some buttons that don't get outlined and/or are blank thus, it's not 100% bang on but, for me, just changing font and background colour for night mode is heavenly.

I had issues with white glare out / white-smokey haze and do not run day mode at all. Night mode is bad as well for, white font colour makes it glarey on a jet black background.

I don't like white font colour but terminal font colour on a greenish blue RGB background like I've setup in all my software programs.

There are other advanced tools such as Stylus and or Tranquility Reader - they do work however, when you need to get things done (GTD), this tool is a global parameter thus, you don't need to learn how to code in HTML and CSS mode just to fix a site's font issue due to poorly chosen colour schemes.

Greatest Extension I've found so far for me eyes. Excellent work mate.