Generating a site navigation pulldown menu

I’m starting to migrate my personal site from RapidWeaver to MiddleMan. Sections of this are falling into place, but I’m not sure how to handle the pulldown navigation functionality. It’s the same on every page and would clearly go in layout.erb. My initial thinking is to write some Ruby code that traverses the sitemap data structure and generates the static HTML. Then I’d need the CSS to style it. I’m a beginner at web development but understand programming.

I came across Generating navigation tree and including in layout while searching this forum but I’m not going to claim to understand the author’s solution.

I’ve seen approaches that use JavaScript, but this is such a common feature on web pages that I have to think there’s a straightforward MiddleMan solution that I can adapt.