Post installation

I'm having trouble installing a separate mobile css stylesheet for my Drupal10 site. Following the recommended syntax on this issue on breakpoints, I updated my libraries.yml file like this:

I have recently upgraded a Docker D9 site to D10. 

I can browse the site and see all my content when in maintenance mode, but as soon I put the site online I get a whitescreen on every page.  Changing the theme doesn't help.  There is nothing in the logs, and the inspection console shows nothing.  I've updated to the current version of everything, I've run updb and cleared the caches. 

I will sometimes see a flash of an unformatted page on the screen that disappears without a trace in seconds.

Any idea where I should start looking?

I use Olivero sub theme but I think to install a starter theme and try to develop something from it myself because I dislike Olivero's page content width limitations and CSS grid utilization.

What is your most favorite general purpose starter theme, and why?

What will you recommend for me based on my problems with Olivero?

What is planned in all that has to do with themes?

• What will be the administration theme?
• What will be the general theme?
• What will be the starter theme?

Even a rumor will do :)

Hello all

I use Drupal 10 and I would like to transfer some configuration items (not all) from a site (source site) to another site (destination site) which is not a clone of the first one.

I would like to know if the following workflow is allowed

I am not a PHP/Drupal programmer so please try to give me a general audience answer.

I have created a region and I want to give that region the main class of another region such as region--sidebar.

How to do that?