Drupal 8.x

I'm working on implementing my site in Drupal 8 and have decided to use the Danland theme. That theme comes with some images that I would like to replace, there will probably be other changes (css?) that I will want to make. I've already had composer replace all of my changes with the original content so updating it in place probably is not the way to go. What's the best practice to proceed? I attempted to use danland as a base theme but ran into errors early on that I'm not sure how to address, they have to do with the template_preprocess_* hooks.

Hello,

I have a problem with submitting a form that is displayed in modal window.
The form is an edit form for my entity.

14 hours ago I could install drupal with composer create-project drupal-composer/drupal-project:8.x-dev drupal8 --stability dev --no-interaction - now installation always fails with following error message:

Drupal 8.5 sites. Looking at Media browser and other features of 8.6. The choice is to add Media entity browser and other things to 8.5 or convert to 8.6 early. Perhaps at the beta stage. Has anyone experience with the 8.6 branch?

What I want is an 8.6 ready to train people in how to handle media the 8.6 way. Adding things to 8.5 is an option but when I read the 8.6 plans, there are what looks like conflicting plans for things like CKEditor integration. Using the real 8.6 would be better.

Hello community!  

The organization I work for is looking for some guidance on choosing a base theme to develop a new responsive theme from. The requirements are the following: