Thanks Mottie. It works like a charm. But still have a problem there.
It works for a specific fixed width declared in the css. The problem is that the thumbnail list is not width fixed. The width grows for each new thumbnail for entry posted. I think going to need some Jquery or something else, because I see that with css only, works wiith fixed width only.
Anyway, thanks again Mottie. That solves me a great way.