How to ensure a value box position stays the same when viewed from different browsers

Hi all,
I have used JavaScript to display a value box in one of my questions and it looks perfect when viewed via Google or Opera, but the position is changed when viewed with Firefox. Is there any anyway to ensure the position stays the same with different browsers? Here is the code:
value_box.style.position = 'absolute';
value_box.style.left = '463px';
value_box.style.bottom = '177px';  
Thank you!