Experiment: HTMLMapmlViewerElement.matchMedia('(prefers-lang: xx)')

This page uses the HTMLMapmlViewerElement.matchMedia function to select map content based on the browser's preferred language setting, in the user's language, ideally.

If your browser isn't set to prefer english or french , the map should display the OpenStreetMap base layer. Otherwise, it will display the Canada Base Map layer in english or french, accordingly.

How to Set or Change Your Browser's Preferred Language (navigator.language)

Manipulating these settings will allow you to see how the mapml-viewer element adapts to different language settings used by users.