How can I modify the "Simple chapter navigation template", or make one like it, where the CSS border is at the bottom of the div rather than at the top?

I'd like to use this navigation template at the top of some pages and thus need the border underneath the navigation rather than on top. I've looked quite a bit on the wikibooks site the last few days and not found the relevant pages on making such a template. How is it done?

Regards, Lars