Introduction to theme.json

[@charleslambert3090]

First-class introduction. Crystal clear -- thank you.

[@hujth6]

great content! thank you very much, realy clears things about theme.json

[@Eroquel07]

Excellent explanation, thank you.

[@cobianzo79]

I wonder... has any developer worked in a User Interface that allows you to set up the theme.json (palette, fonts, headings, ... )?
I know that some themes, like Astra, allow you to set this up, but I was thinking more about a way to edit those fields from a plugin independent from the theme, and save the changes into the theme.json, so you can easily export it to any other theme