Design of terminal when multiple tabs are open

I am currently testing 13.04, but I was quite disappointed this very ugly design from 12.10 was not fixed: I use the terminal with black background and white foreground color (apart from that: default Ambiance theme). It looks very nice as long as you don't open multiple tabs. As soon as you open multiple you will be hit by a lightning... Suddenly the whole terminal gets an ugly white frame and the tabs themselves (instead of being white on black, too), are big white bars, too. How come this has not been detected by anyone half interested in good design (about 70% of the programmers I know work with white on black, not black on white. So I assume a lot of people must have seen this).

The question is how to fix it. In 12.10, I fixed it a bit (but that does not remove the ugly white bars called tabs) as follows:

1) /usr/share/themes/Ambiance/gtk-3.0/gtk-widgets.css
2) set padding and border-width of ".notebook" to 0px.

Not very elegant... as I said. But I'm sure some experts in the field would easily know how to fix it. At least I hope very much.