Icons in window borders

[MartinW]

One thing I like about Mint is how customisable it is, and I've got it looking (I think!) really rather cool, with a dark theme and Mint-X blue icons and controls. However, there's one thing that I can't seem to change, and that's the colour of the icons within window borders (which I have on Mint-Y dark, as I prefer dark borders), which still come up in standard Mint green. It's hardly a major problem, but is there a way to change them to the same blue as the other icons?

This is Mint 20.1 Cinnamon, btw.