Question about windows borders in Ubuntu Gnome

[joangg]

I'm currently using Ubuntu Gnome 16.04 in a virtual machine and I've noticed that there is a line between the window border and the window itself, and I don't like it. I can see it in the latest versions of Fedora too, but in Debian 8.5 this line doesn't exist and I prefer it that way. Is there any wat to remove this line?

Ubuntu windows (with the said line):

https://i.gyazo.com/abb4cb1f799ad0a861355f1b41d6bb48.png

Debian windows (without the said line):

https://i.gyazo.com/00b96b73eeca7184c0c22ee2304620ad.png

[grege2]

The Debian version looks like it is using Numix as the theme. Try a few themes and use Tweak Tool to change the GTK+ Appearance settings