[mux-player-react] Docs/guidance for creating a custom theme in React

[vimto]

Thanks for the work on media-elements and media-chrome, they seem like a really a well designed ecosystem.

We'd like to use MuxPlayerReact in a Next.js app with custom icons for the controls. This seems to require a custom theme - are there any docs on how to do this within React?

To confirm it's possible, I've tested rendering MuxPlayerReact with theme="minimal" (along with import '@mux/mux-player/themes/minimal'; in the same file). This works, albeit with a console error message: [mux-player 3.5.1] <media-controller> failed to upgrade! which doesn't seem to break anything.

For our own custom theme, do we need to wrap template we create and media chrome elements we use with the ce-la-react, similar to how player.style themes such as minimal are published? Or is there a simpler inline way?

Thanks for any guidance!