When I use Firefox in Linux Mint, everything has a kind of green shade to it. The monitor is fine. I'm guessing it's Mint branding.
How do I remove it?
My original question wasn't clear - it's not the browser chrome that has the green shade, it's the pages themselves.
Here's a screenshot - compare with the actual page, and you'll see what I mean. To prove it's not the monitor, I right click on the photo of the sausages (I bet that's the first time that word's appeared on unix.se.com!) and save the image to the desktop. Then I view the image by double clicking on the new file and it displays fine.
There are two plugins installed -
Mint Search Enhancer and
Stylish - deactivating these makes no difference.