Nemo Desktop | Change Focus Item Appearance

Seems to be similar to my issue when I replaced Thunar with Nemo as default on XFCE DE.
One solution is posted here: Zorin 16 Lite good for Asus H97m-e? - #7 by Aravisian
but I don’t know if it is what you’re looking for.

PS - the very next post on that thread I linked also has a link to another thread where I had installed Nemo a different way. Not sure if that helps either.