Product Thumbnail

It happens that product thumbnails don't have the right size.
This is how they appear on your demo:
(Please notice how they fit in width with the gallery below):
http://screencast.com/t/QXOzNTiOFb6r

And this is the result in our env:
http://screencast.com/t/uoFHMB94tSm

Any hint about that?

Thanks