Theme development

I am building my first Drupal site and using the layout builder to build a layout for the home page. How does one go about creating a section within a section? Use case here is that I would like to have an "outer container" and an "inner container" so that we can style such sections / containers differently. A layout / site may have multiple different backgrounds for sections (different shades) and I would like to apply styles to an outer section but create a section within that where my content blocks goes.

Any ideas? 

I'm new to Drupal and tasked with building a website in Drupal 9.3. I'm not a programer.  So please excuse my ignorance. 

What's the best, and easiest way, to override the default theme and have another theme used for a specific page/node. 

I want to use a custom theme on several pages on our site but I can't figure out how to have that theme applied to the target pages instead of the default installed theme. 

I've been searching for two days now and I can't find anything with clear instructions. 

Hi I have created a custom template for my menu.

I have placed the menu (as a block) within a region.

I have created another custom block which I am trying to render within that menu block, rather than as a seperate block.

However, nothing renders. I have tried printing something similar to below but nothing ever gets outputted.

$block_id = $myblock;
$block = \Drupal::entityTypeManager()->getStorage('block')->load($block_id);
return $block;

I need to get current region or current block where is node in node hook

hook_theme_suggestions_node(array $variables)
{
  $region_of_node = //I don't know how to get it
  $block_of_node = //I don't know how to get it
  $suggestions[] = 'node__'.$region_of_node.'__'.$block_of_node;    
}

I don't need both just one, region or block. Please help

Hello everybody, I'm trying to upgrade the old "Professional" theme developed by Devsaran for Drupal 7.x to make it work into Drupal 9.3.0, in Windows 10 Pro 64 with Xampp Apache 2.4.48, php 8.0.7, so I created just an empty standard test site with Bartik theme as default, I followed all the instructions given in many tutorials to create the proper files, .theme, .info.yml, .libraries.yml and the .html.twig files, but I didn't have any success, I checked the format of the files, the paths of css ans js files and I respected all of the standards given in many forums.

Hello

PHP 8

APACHE2

I have this message when I want to access a page to edit :