How can I disable horizontal scroll in textbox for FireFox?

Right now 1 textbox has vertical scroll and other textbox has horizontal scroll.
It only looks like this on FireFox but it looks ugly.
http://jumbofiles.com/example.gif

I used this code but it only worked for IE not FireFox:
style="overflow : scroll; overflow-y: scroll; overflow-x: hidden; overflow:-moz-scrollbars-vertical;"...