There's 2 things I'd try here - firstly check that there's no margin above the navigation links.

p { margin:0px; }

or if you're using lists then

ul, li { margin:0px; }

If this still doesn't work then you can use the "position:relative" and then do "top:-10px;" - now this will move the IE as well, you will need 2 style sheets, one with just fixes for the other web browser and so when defining your style sheets you will need to do a web browser check to see what the user agent is and then pick the correct style sheet.