@crazycells This proved to be much harder than I anticipated. The issue here is that the background is already transparent, so if you make the rosette itself transparent, you can no longer use the :after
element as it’s designed to fill in the check mark - not the remainder of the image.
The only real way this would be possible and without losing yourself in overlapping CSS code would be to edit the image with Illustrator, or InkScape (Open Source) and change the rosette and border colour according to taste.
Ultimately, it’s not possible to change this on the fly using CSS without significant work. As a result of this, plus your idea yesterday, I have elected to use a Font Awesome icon (Shield with Check Mark) and have made it “Sudonix Orange”.