Centering the Add to Cart button

I want to center the Add to Cart button (or in my case, since I'm in showroom mode, it says "Contact Us" instead of "Add to Cart") when viewing an individual product. I'm using 1.3.9c.

I found the following in my stylesheet.css file:

/*Shopping Cart Display*/
#cartAdd {
    float: right;
    text-align: center;
    margin: 1em;
    border: 1px solid #000000;
    padding: 1em;
}

I tried commenting out the float:right line, and it just makes the button stretch across the whole screen. Any help or thoughts from a CSS whiz out there? Am I even looking in the right file?

try float: middle, instead of commenting it out

10west:

try float: middle, instead of commenting it out

No such thing as float: middle? Anyways, I tried it and float:center but they both do not work. I'm guessing I need to add some invisible boxes on the right and left side of the Add to Cart button to make it float properly without stretching.

Other thoughts out there? If I figure something out on my own I'll update...

Float can only be left, right or none. Floated divs automatically shrink to just fit their content width, so if you remove the float, you need to explicitly set the element width if you do not want it 100% width. No invisible boxes are needed; margin: auto; will give the element equal left and right margins, centering it.