Download the attached overrides_custom.css file and follow the steps below
1. Login to CABI server as superuser.
2. Go to Repository -> Themes -> ca_theme and export the overrides_custom file(in order to have a backup).
3. Right click on the same file and select Edit. Then browse for the attached overrides_custom.css and select submit.
4. Once this file is uploaded, retest the issue with Firefox.