It's doing that because there is not enough room in the space avialable for three items. Probably there is some setting splitting up the space into 33% areas, but then there would be another setting telling the browser to leave room for margins or something like that, so the total of 3 x 33% plus margins is greater than 100% and the line wraps.

Having said that, let's see if we can fix it. ... ...

Oops! First step, get rid of the multiple extra stylesheets. You've got 4 redundant ones named with dates. Because of the way Zen Cart handles stylesheets, all of them are being read by the browser. So either delete them from the server or rename them with something other than .css as a file ending. Won't be able to help until you do that.

Rob