Block editor styling missing

With Sage 10 theme installed I seem to have lost all the default core styling for the admin block editor.

Is there a way that I can easily restore those default styles?

Yes, see this example:

$relAppCssPath = asset('app.css')->relativePath(get_theme_file_path());

I’ve added that bit of code to setup.php and the block editor in admin remains as it was before I did. The styling is missing. For example, each block added to the editor runs from the left edge to the right edge of the block editor area. I am using Docker for my local environment, not sure if that makes a difference.

If I switch themes from Sage 10 to Twenty Twenty Three (or any other theme) the correct styling returns.

I was hoping to use Sage 10 for upcoming projects but I find myself spending so much time trying to get the simpler stuff to work (unsuccessfully) that it concerns me about the more complex stuff that I could face further down the development process.

Check out this Sage 10 Full Site Editing sample theme:

Do these adjustments help?

This is expected behavior until you configure and style the editor

I’ve installed your theme but I get the same results as mine.

Why does Sage remove the styling? I want to restore the default core styling for the editor. I have been unable to do so with the suggestions thus far.

Sage doesn’t remove the styling. You can’t compare Sage to a core theme that is fully configured and styled for the block editor. You must configure and style the block editor for your site. Sage is a starter theme.

I highly suggest reading about theme.json and even looking into the core themes to see how they use it.

OK thanks. That makes sense now