However, I have a problem with the buttons displaying properly in both IE and Firefox. I have installed OpenCart 1.3.4, and I have modified some of the files to meet my needs.
I generally use FireFox 3, so I never noticed that on IE 6 and IE 8, and the buttons (the ones that slide to fit the text, such as "Add to Cart") do not load properly - no text is shown and only the right "end cap" graphic is shown. If I select text with my mouse, the text magically appears, and the remaining bit of graphics disappears.
For example:

This is IE 6 and 8, showing the disapearing button.

This is with the area selected with the mouse
On Firefox 3, the buttons look great. On older versions of Firefox (such as version 2), the same buttons are also altered, but in a different way. The button displays fine except for the right "end cap", which has slid and off-set half-way down.

Can someone help me understand why this is happening? I know version 1.4 just came out, but after spending 4 weeks working steadily on customizing the theme and text of the cart, I shudder at redoing it again.
Thank you so much for helping me!
-Jake