Bottom Widgets different widths

I have a Widget of “Bottom” I have 3 areas: (1) A Youtube video (2) Some text (3) Some more text. I would like the Video to be bigger. How?

I think I can do this if:
(1) In the NB3 Theme layout, set Force Position = On
(2) I think I need to modify style.css. But, what to put?
I see some #rt-bottom tags. But, is that what I want?

This did NOT seem to work.
#rt-bottom .left {
width:600px;
height: 450px;
padding-right: 20;
}

Please help!!!