Toggley от Farid Zelli

A simple button that toggles between your favourite Light and Dark themes.
To use it, simply tap or click on the icon to switch themes.

Toggley works best with Dark Reader.

The default keyboard shortcut is Ctrl+Alt+0.
See Manage extension shortcuts in Firefox for more info.

Experiencing a problem? Please ensure that:
"privacy.resistFingerprinting" is set to false in about:config
You have enabled "Use system colour scheme" in Dark Reader

This lightweight add-on is fully open-source.