Getting rid of faint grey box around inserted image

Hi, I have a problem that I saw addressed a few months ago, but the custom CSS code didn't work for me. When I insert an image into the body of the text of my post, there is a faint grey border around it that I can't get rid of. I don't mind the larger gray border on the images that I post at the top of the page, just the ones I put into the actual post itself. I remember with an earlier version of Catch Box Pro that there was something you could do when editing the photos to get rid of the box, but I can't seem to find that option now. Any help you can provide would be most appreciated! My URL is arcturusastrology.com Thanks! Lynne