I solved the problem for me (workaround):
Add this file
~/.config/gtk-3.0/gtk.css
.menu { border: 2px solid DarkSlateGray; background: #EDEDED; }
I solved the problem for me (workaround):
Add this file
~/.config/ gtk-3.0/ gtk.css
.menu {
border: 2px solid DarkSlateGray;
background: #EDEDED;
}