I have set my gnome-terminal colors green on black (easy for my eyes).
Unfortunately the gnome-terminal application in Ubuntu 14.04 LTS does not have a border by default, making it difficult for me to get hold of the boundary of overlapping terminal windows, especially I have set my background to black as well (to conserve battery life).
Assuming Ambiance is the active theme, the following change is how I get the terminal border back:
$ vim /usr/share/themes/Ambiance/gtk-3.0/apps/unity.css
-UnityDecoration-extents: 28px 0 0 0;
-UnityDecoration-extents: 28px 1px 1px 1px;