Thread:Extension talk:Echo/How do I change the background colour of the Echo notification badge?

I added the following CSS to "MediaWiki:Common.css": As a result nothing happens. No caching involved neither on the wiki nor at the client side. Other CSS adaptions get through immediately. I am pretty sure that I picked the correct classes so I am utterly puzzled for the reason why nothing happens ... This is pretty frustrating so any help is appreciated. Thanks and cheers