Fix Firefox dark text input on Ubuntu 18 with dark themes

The text input box in my Firefox 60 has ==dark text on a black background== (see below)

The reason is I’m using a dark theme called Adwaita-dark on Ubuntu 18.

It turns out to be a generic problem people are facing. I’m sure someone will fix it down the road but here is the quick fix if you can not wait:

1. Create a desktop icon:

gedit ~/Desktop/Firefox.desktop

2. Fill the following content & save the file.

#!/usr/bin/env xdg-open
[Desktop Entry]
Version=1.0
Type=Application
Terminal=false
Exec=env GTK2_RC_FILES=/usr/share/themes/Adwaita/gtk-2.0/gtkrc GTK_THEME=Adwaita:light /usr/bin/firefox
Name=Firefox
Comment=Firefox
Icon=firefox

3. Right-click on the Firefox icon you just created on your desktop and click:

Properties -> Permissions -> Allow executing file as program

4. Double-click the Firefox and click Trust and Launch (you only need to do this once).

5. Done, enjoy the dark color text on white text inputs.

Cross-posted from https://lsm.ai/fix-firefox-dark-text-input-ubuntu-dark-theme/.