Want to suppress navigation bar tab alpha listing of pages

I’m using the greenline-10 style sheet. Pages are displayed in the tabs across the top of my site in alpha order and that’s NOT the order I want them. I’d like to use the numerical order set for each page. I’ve played with the style.css for quite awhile and can’t figure our how to make the ordered list an unordered list. Any suggestions on where I can find the exact code and change it?