Change 'Customise' dialog tab text colours in Linux

LibreOffice 5.2 on Linux Mint 18 Mate with ‘libreoffice-gtk3’ installed (the theme was ‘Windows 95 hideous’ before I installed the gtk3 package).

Most of the UI text colours are fine, but some of the colours in the ‘Customise’ dialog are wrong (eg, white text on pale grey background) making it difficult to read and/or ugly.

Is there any way to change just those colours in the UI?

(I’d upload an image, but apparently I don’t have enough points.)