Hi Salvadori
Just to keep me right amused, I went back to my app and first ran it under Chrome with no changes and I got colour.
Hmm I said.

I also figured out how to check in Chrome developer tools to see which application.css is loaded and it had the right one.

So I returned to the Sample App. It still has no colours with Chrome and colours with Edge. In Chrome I checked to see which application.css was loaded and it was the right one that you provided.
It moments like this when I wonder if, in fact, we are all part of the Matrix and I got a controller with a really weird sense of humour.