(originally posted in Slack: https://getgrav.slack.com/archives/C3Z7KN6MC/p1490592651037943 )
With the featherlight plugin, I can do this markdown: 
… and Grav processes the classes and the plugin processes the necessary lightbox DOM manipulation etc
But with remote URLs (static Streetview URLs specifically), this doesn’t work
e.g. 
(I have an API key BTW but not posting it here, so that URL won’t work without a real key)
It half works, because the classes get pre-processed by Grav, but the featherlight stuff doesn’t.
Does anyone know if this is a bug, or if there is a good workaround? I figure I can probably write a shortcode extension once I figure out the desired target markup. That’s one workaround.