Floating layer: position changes in IE and FF, why?

Take a look at this page (http://nataliehijazi.com/Tester/mainpages/about.htm) in both IE and Firefox, notice that in IE the arrow is positioned within the borders of the image which is exactly where I want it to be, but in FireFox it's below. I don't undertsand why that happens and really care to get it fixed, IF possible. Suggestions?

p {margin:0;}

How weird, I already set the page's margins to zero, but that workd! Thanks :thumbsup: