Site Editing & Responsiveness - Breakpoint specific block settings (especially navigation block).

[Addison-Stavlo]

Note - Il initially note this as for 'navigation block' as it seems to be one of the most necessary places for this sort of control. But in general we probably need a way to enable something like this across the board? 🤔

The Problem

In the Site Editor we allow editing content in device previews such as mobile and tablet:

This could lead users to believe that the settings their apply inside these device previews should apply specifically to that device size, while in actuality it effects the design at all screen widths.

An example

Lets use the navigation block as an example. At full screen with it may look best when set to the 'horizontal' variation:

But as soon as we get to tablet and mobile, it is clear we would want to use the 'vertical' variation at these screen widths:

Potential solutions

Allowing block settings set in these modes to be specific to that screen size only may help empower creation of well responsive site layouts and content.

[mtias]

Closing in favor of #22824. The approach we want to take with these is one of "better defaults" rather than per breakpoint settings, which can get rather complicated (as seen in #19909).