gnome-terminal-restyle

gtk.css

# This should go into ~/.config/gtk-3.0/gtk.css
@define-color bg-grey #222;
@define-color active-grey #333;
@define-color border-grey #555;


TerminalWindow .notebook {
  border: 0;
  padding: 0;
  color: #eee;
  background-color: shade(@active-grey, 1);
}

TerminalWindow .notebook tab:active {
  border: 1px solid @border-grey;
  background-color: shade(@active-grey, 1);
}

TerminalWindow .notebook tab {
  background-color: shade(@bg-grey, 1);
}