Center a DIV to the center of page regardless of screen size

Question

I want to center the below div container to that the site appears in the center of the page, regardless of the screen size.

http://penarthpc.com/~droneboy/

I've played around a little bit but appear to be missing something.

Answer 1

The solution to this problem is using auto for margin in the CSS AND providing some width to the DIV itself:

div.centered {
margin-left:auto;
margin-right:auto;
width:80%;
}