I know there are lots of FF/Chrome CSS questions, but I can't seem to find this exact one.
Here is a JS Fiddle showing the problem: http://jsfiddle.net/ajkochanowicz/G5rdD/1/
(Apologies for the long CSS, this was copied from the site.)
Essentially, Firefox and Chrome are giving me two different values for the inner most width of the button, 4 and 6. I'd like it to be 4 or less for both. What is causing this?