Align CSS Button in Center

Align CSS Button in Center

I've tried using posiotion:center and middle in the CSS and in the HTML
code I've tried align="center;middle" but nothing seems to work. I need
the button to be aligned in the center of the page and not to the left.
I've replaced several codes but still nothing. I've never had this problem
before but I guess there's a first for everything.
http://jsfiddle.net/LnSRb/
Here's the HTML code:
<div id='cssmenu'>
<ul>
<li class='has-sub last' id="iefix"><a rel=nofollow href='#'><span>Choose a
model</span></a>
<ul>
<li id="iefix"><a rel=nofollow href='#'><span>iPhone
3GS</span></a></li>
<li id="iefix"><a rel=nofollow href='#'><span>iPhone 4</span></a></li>
<li id="iefix"><a rel=nofollow href='#'><span>iPhone 4S</span></a></li>
<li class='last' id="iefix"><a rel=nofollow href='#'><span>iPhone
5</span></a>
</li>
</ul>
</li>
</ul>
</div>