Why do I need to enable the Drupal Bootstrap theme when using a Bootstrap subtheme?

Question

I'm trying to learn how to use the Drupal Bootstrap theme to create my own subtheme. I've added the Bootstrap theme to my drupal/themes directory, and chosen SASS as my sub-theme starterkit (i.e. I've copied drupal/themes/bootstrap/starterkits/sass to drupal/themes/mynewtheme).

I understand the concept of how sub-themes work: the sub-theme inherits the parent theme's resources. But I don't understand how it works in the case of the Drupal Bootstrap theme. Once I install the bootstrap framework into my sub-theme (per the instructions on the Drupal Bootstrap sub-theming instructions page), what resources is the sub-theme inheriting from the main theme?

Answer 1

Why do I need to enable the Drupal Bootstrap theme when using a Bootstrap subtheme?

You don't. You simply have to define in your subtheme that you're making Drupal Bootstrap your parent theme.

what resources is the sub-theme inheriting from the main theme?

The templates and anything tethered to it.

Templates that you don't override on your subtheme gets delegated to the parent theme, in this case, the Bootstrap theme. Anything that the Bootstrap theme doesn't override gets delegated to the core themes. If I remember correctly, the Bootstrap theme overrides a lot of the templates. If you turn on template debugging, you'll see the hierarchy of the template suggestions.

Since the templates also define additional things like favicons, extra CSS, HTML boilerplates, and that stuff (html and page templates especially), if you don't override them on your subtheme, you get Bootstrap's which loads whatever is in there.