How do I control vthumb border?

I have successfully created an mbox in my article, but the thumb has no border (gray one on the demo site). When I roll over, the black border appears and makes the image move a bit. This makes the whole page move and other elements get out of place.

code:

{mbox:http://www.vimeo.com/11618440/|640|480|title=Plus and Minus |vthumb=logo/plusandminus.png|height=150|width=200|caption=Plus and Minus}

Page URL (won't be a good example of the error, once we fix it...LOL!)

Data Visualization

the png image is exactly 200x150 pixels.

- Is there a way to not make the rollover border show up?
- Is there a way to add the gray border to the original thumb?
- Can I change the colors and widths of these borders?

Thanks!!