I was trying to install ubuntu-desktop package in Ubuntu-Gnome(gnome shell). Using unity-tweak I set theme as Ambiance. But only gtk2 applications are looking good. All gtk3 application has ugly border(header bar) and background(sometimes). I have attached a screenshot.
What is the default gtk3-theme-engine in Ubuntu unity?
Edit
if I run gtk3 application with root permission then theme is okay. I also created a new user but result is same.



