Theme development

I need to build a theme style with multiple tabs. But i found it anything theme similar with it.

Hi I can't insert class in child item of main menu and remove existing. Part of my code looks like this:

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