Marking up a map legend for the web?

I have a map of user feedback (it’s very cool, and if you or someone you know is in or around Dublin, California, check it out). I want to add a map legend, but so far I’ve come up bust on how to approach it in a way that is both accessible and responsive.

While that particular map uses the Google Maps tiles, and there is a map legend-y thing in the API, it’s very basic. I’m convinced I need to include it in the content after the map.

So… where are guides or examples in the wild of proper map legends marked up in HTML? :slight_smile: