Need help with horizontal menu with icon centered above each link

So far I have something like

http://jsfiddle.net/7KxTQ/

but the problem is I can't figure out how to 开发者_如何学Gocenter the icon

---

To #mainnav ul li a:link:before, #mainnav ul li a:visited:before, add:

margin: 0 auto

Live Demo