I love the approach of having it show you the code (and diff) and control on writing it back. This seems like it may be very useful!
As an AOLPress user back in the day, it's both really surprising that in 2024 we don't have more WYSIWIYG tools, but also understandable because of how hard it is to design one.
Most tools end up trying to find a sweet spot between targeting a developer and targeting a designer, and as a result end up doing neither well. There's also the problem of what kind of code it generates, and how to generate good/maintainable code that doesn't tie you to the WYSIWYG tool for the rest of its life. I haven't had a chance to try this yet (though I plan to) so I'm not certain where it falls on each of these, but from the video I get the impression that you are well aware of these challenges.
Thanks for sharing, and thanks for making open source!
Edit: Adding a couple of question:
1. Are you planning to monetize? If so, what are some of your ideas?
2. What is the grand scope for Studio? It sounds like the immediate focus is on editing styles. Are you planning to keep the scope limited to that, or would this eventually become an everything-you-need-for-building-a-website type of tool?