Mendeley toolbar appears in gray and bad-looking

Hello. I have a little problem regarding the toolbar of the Mendeley extension for LibreOffice Writer. The extension works fine, but the toolbar appears in gray, I mean the color of the font (it seems as if it is disabled). You can see what I mean in the following image:

I have updated Mendeley, uninstalled and re-intstalled the plugin, buy it doesn’t work.
Any suggestions?

Thanks!

Write to author of extension and ask him about this problem. May be this extension didn’t test for last version of LibreOffice…

I managed to the plugin to look OK by changing the GTK theme in Ubuntu with the tweak tools. I was using Numix and changing to HIgh contrast made it look fine. BUT the extension is not working for me, Ubuntu 16.04, using the latest Mendeley and LIbreoffice.

Thanks! I changed the theme and now it looks OK, and apparently working fine.