I am a newbie to zencart, but fast appeciating its power (but not its complexity!)

anyway, if you go to my site at:
http://www.pageplusdirect.com/zencar...e_plus_refills

The "add to cart" images have a light gray box around them. I don't think this has to do with "a img {border:none;}"

The program just puts a box around certain items, like "add to cart" items.

Can someone help me figure this out? Thanks!