Featherlight configuration

I have installed this plugin and it works fine. However I would like to modify the presentation to look like this excellent site
Is it possible just by modifying the configuration and CSS or do I need to change the code?

That’s really beyond my expertise to help you with. Probably best to contact the author of the featherlight plugin and ask him that question. The Grav plugin merely implements that JS plugin in a Grav-friendly way.

I’m not the author of featherlight, and only know how to use it, not really anything related to customizing it.