Some past discussions of Decker:

4 years ago: https://news.ycombinator.com/item?id=33377964 - "Decker, a platform that builds on the legacy of Hypercard and classic macOS"

2 years ago: https://news.ycombinator.com/item?id=38985409 - "Decker – A HyperCard Replacement"

2 years ago: https://news.ycombinator.com/item?id=40292181 - "Decker: A reincarnation of HyperCard with 1-bit graphics"

It's both native and web-based. Web version: https://www.beyondloom.com/decker/tour.html

Click File -> Cards... to see how the tutorial is constructed.

I can only recommend looking at all the Decker author's projects. He's done work on APL languages, GUIs, interactive programming, etc. https://beyondloom.com/things/index.html

A cool person making cool things!

If y'all never seen Decker, it _is_ cute:

https://github.com/JohnEarnest/Decker