outlook.office.com - see bug description

[webcompat-bot]

URL: https://outlook.office.com/mail/

Browser / Version: Firefox 104.0
Operating System: Windows 10
Tested Another Browser: Yes Edge

Problem type: Something else
Description: Facebook Container add-on breaks Outlook Web Dark Mode
Steps to Reproduce:
I logged into my work computer as usual and noticed part of my e-mail's sections were illegible because they were suddenly on a white background. I use Dark Mode in Office Web, so the text is white, as well, so I had a white-text-on-white-background issue.
I reloaded the page, separated it into a new window, toggled Dark Mode on and off (that's how I figured out that was causing problems). I contacted Microsoft Support - they told me to try it in Edge, works without issue. Restarting Firefox didn't help, so they suggested refreshing. After refreshing, the problem was gone!
I decided to add my usual add-ons one by one to see whether they played a role, and I discovered I could toggle the sudden white background on/off by enabling and disabling the Facebook Container add-on.
I noticed on the Manage page for Facebook Container it was last updated on 8th September 2022, so I'm guessing that your last update interferes with Outlook Web's Dark Mode. Weird.

View the screenshot

Browser Configuration

• None

From webcompat.com with ❤️

[softvision-oana-arbuzov]

Thanks for the report, it seems to be a known issue under investigation.
For more info check here:

• https://bugzilla.mozilla.org/show_bug.cgi?id=1789822
• CSS fonts rules overrides website ones mozilla/contain-facebook#857

Closing as duplicate of the above.

[qa_36/2022]