How to get rid of the red colour on the Don't Save in the SAVE dialogue box

I just changed from Windows 10 to Linux Mint. Now when I go to Save a file, in the Save dialogue the “Don’t Save” button is coloured red, which it wasn’t in Windows. How do I get rid of the red colour?

The Mint docs seem to imply this is controlled not by the system but by the icons under Tools > Options > View > Icon Theme. The icon themes shown are Colibre and Colibre SVG, and both have the red. I’ve read I should install Colibre Legacy extention, but this when installed tells me it’s the same as the Colbre SVG already there.

So HOW??? please can I get the old-style Save dialogue with no colours?

This issue is that here in the UK, while of course traffic lights have red to mean stop, in other contexts it’s very confused whether red means “Start” or “Emergency Off”, so this colouring doesn’t protect against errors, but rather makes a lot of confusion.

With many thanks.