Transaction verifier circuit and CRS

I would like to see an educational blog post about how the circuit(s) are made up in Sprout and/or Sapling, and what is included in the CRS, in a blog post similar written by Ariel about zkSNARK-s in general last year. I am also in general intersted how is the “Pi” proof generated in layman’s terms.

Many thanks in advance! BR Gabor