I found that if I add

ul.rMenu li {
position: relative;
left: 75px;
}

...I can move the menu bar over to the right to center it. Problem is that the drop down child menus don't line up with the parents. They end up being over to the right, beneath the parents. How do I change this so that they open directly beneath the parent?

It's better to use %page-center for a centered menu.

That seems a lot simpler than the other suggestion. Where would I place that code to get the desired effect?