This repository provides dark themes for some services I use in Franz.
Clone the repository, and set symbolic links in Franz's recipes folder to the respective darktheme.css. Then, in Franz go to File -> Settings -> Your services ->SERVICE, and turn on Enable Dark Mode.
Default path for the recipes in Windows is %AppData%\Franz\recipes. So for WhatsApp you can run following command on the command prompt, from the root of this repo:
mklink %AppData%\Franz\recipes\whatsapp\darkmode.css whatsapp\darkmode.css
Default path for the recipes in Linux is ~/.config/Franz/recipes. So the command is:
ln -s whatsapp/darkmode.css ~/.config/Franz/recipes/whatsapp/darkmode.css