Man you have bigger problems. If you visit a product page like this one
http://www.greatlakesvacuum.com/GLV-F-Lube-Vacuum-Pump-Oil-5-Gallons.html and shrink the browser a little to accomadate a small monitor, the description and add to cart are off the screen. Well that is fine, but only if a scroll bar appears that allows you to scroll over to it. In his case it leaves a user with a small monitor or with a small window open no way to get to the button. Imagine what it does on a tablet or phone.
Back on topic, Steve is then also correct in telling you to edit the css.
You have this style definition in your css:
button.add-to-cart-button {
width: 33px !important;
}
Removing this will allow the button to fit the text.
Edit: Steve, you are too fast...
