How to properly configure Maizzle in a Rails app?

I found few reference about it, include a Podcast with Chris... but no real end-to-end proper integration.
So far I have read https://github.com/maizzle/framework/issues/346 and the Mix & Go (box & YT video) but nothing really explain how the global mail layout should be configured, what should be tweaked in the config.js or postcss (the post on Github seems broken for Maizzle 4.5.0) etc.
for the time being, my idea is to have a generic <%= yield %> in the mail layout... but that's a bit killing the purpose.
Any suggestion?