Change background by tag

Hello,

I found this post on Reddit which offers a seemingly clean way of styling cards based on tag. I wanted simply to have a different background based on the tag for starters.

However, when I apply it to the reversed card template (I would like this to be applied to all my reversed cards), nothing changes.

EDIT: Curiously, the changes are visible in Ankidroid, but not previewable on the desktop version! If I change the background using CSS on the desktop and try to preview, I don’t get an update. I am able to preview them on Ankidroid, however. Might be worth posting this on a separate thread.

Is the solution in the Reddit thread still compatible with Anki Windows 10 version 2.1.44?

What do I need to do to change my cards’ background based on tag? Is it possible?

Apologies if this has been asked multiple times before. Any help will be appreciated.

Thanks.

EDIT: It appears to be an issue with Anki on desktop. If I save changes and synchronize, I can preview the cards on Ankidroid and the changes work as expected. Might be worth checking this issue on a separate thread.