Drupal 8.x

Greetings,
I have installed the module 'Menu Trail by Path', cleared the caches, refreshed the concerned menus and.. nothing.
I did search for a solution for a few hours but couldn't get to find anything that could help me solve this.

Used with : Pathauto, Superfish

example > http://mxm.heyitsbeing.fr/guides

Hi,

how can i remove the div around branding block or from other blocks? I think i have to copy some template files into my template folder. But which files do i have to use and from where i have to take it? From core/themes/stable/templates/... or from core/modules/system/templates?

Thanks for helping!

Hello Everybody, I want to learn Drupal, tried WordPress but I do'nt like it.
While installing Drupal 8.3.5 I get this error;
Error
The website encountered an unexpected error. Please try again later.
Drupal\Component\Plugin\Exception\PluginNotFoundException: The "comment_default" plugin does not exist. in Drupal\Core\Plugin\DefaultPluginManager->doGetDefinition() (line 52 of core/lib/Drupal/Component/Plugin/Discovery/DiscoveryTrait.php).
Drupal\Core\Plugin\DefaultPluginManager->doGetDefinition(Array, 'comment_default', 1) (Line: 25)

Hi:
I am going mad here, my default theme is zircon and when I view the page it is using bartik theme's logo.svg file, totally crazy. I am not sure how that is happening and why.

Under page.html.twig

 img src="/core/themes/bartik/logo.svg" alt="Home" 

How could this happen ?
Do I have to replace that logo.svg in bartik with my logo ?

Hello, :)

If there is perhaps Tutorial videos or instructions, around the design for a well-chosen Theme
to adapt or has somebody collected there already experiences?

In general to the design / construction of contents I have a few questions: