A: Hey Thomas,

Thanks for your question. And yes, you can certainly use Microthemer to style Gutenberg content, as you can with any kind of WordPress content. The basic workflow is to load the frontend page inside Microthemer.

Optionally you can hold the Ctrl/Cmd key and click through to the Gutenberg editor from the WP toolbar, thus loading it inside Microthemer temporarily. But this would just be to make content changes. It's not possible to select elements for styling when they are rendered as part of the Gutenberg editor (only on the frontend).

The HTML mark-up in the Gutenberg editor is very different from the frontend, and so the CSS would not work consistently in both contexts - at least with the CSS Microthemer generates using the point and click options. There are some options for more technical users, whereby you add a class to a block using Gutenberg and then target just that single class in Microthemer.

You would also need to enable the option in the preferences to "Support admin area style loading". The benefit of this is that you can make content appear the same in Gutenberg as it does on the frontend. But it takes a bit more care, which may not seem worth it for everyone. The following video, which covers the various options you have for loading Microthemer styles, talks about this subject at the relevant seek point:

https://themeover.com/load-wordpress-css-on-specific-pages/?seekTo=495

But as I mentioned at the start of my answer, the standard workflow of styling frontend Gutenberg content in Microthemer is very simple - just point and click on the elements you want to redesign.

I hope I've covered some relevant info here, but let me know if you had a specific Gutenberg workflow or issue in mind that I haven't addressed.

Cheers!
Sebastian