Ok, I’ll need to ask stupid question. Can someone actually explain this - I have style A (that is what I see in text editor in dashboard when Gutenberg plugin is active) and I have style B (that is what I see in front end when I activate my theme). Those styles are different. I also have style C - that is what I see in front end when Gutenberg ready theme is activated, and that is the same as style A.
Now, what should be edited to make theme compatible with Gutenberg? Style A to match my theme or style B to match editor? Style A is not the same as my theme so why would I change my theme to make it the same as Gutenberg editor? That would actually change theme’s design. Changes to margins and paddings would also make backward compatibility issues.