Is https://mjml.io/try-it-live open sourced

[freizl]

I was curious where does those validation rule exists?
e.g.

mj-text cannot be used inside mj-section, only inside: mj-attributes, mj-column, mj-hero

I looked at the mjml-validator package, which looks like core but no actual rules live there.
(Assuming the registerRule will be called some where to actually create validation rules)

In addition, even though there is validation errors, the page still render properly.

Thanks!

[iRyusa]

Dependencies are defined here https://github.com/mjmlio/mjml/blob/170db3f09b0e2d49e95167314134ad4377b29588/packages/mjml-preset-core/src/dependencies.js and most rules rely on a pseudo-typed attributes definition in components