This test image shows how wildly different Safari positions text inside a box vs Firefox (Safari
Have you tried using the Reset at the top of your stylesheet file??
The goal of a reset stylesheet is to reduce browser inconsistencies in things like default line heights, margins and font sizes of headings, and so on.
You can find the explanation & the code here: http://meyerweb.com/eric/tools/css/reset/
I hope this would help you!