Sub-sub Theme Not Inheriting CSS I am trying to extend the Thunder Admin theme by creating a sub-theme in it. This is my first time making a sub-theme in Drupal 8 (other than from bootstrap starter kits).

I would have thought that a basic sub-theme would have inherited the css and js from its parent as is explained here

All I can see that I should need to do is to create a directory i.e. my_theme and create my_theme.info.yml and my_theme.libraries.yml.

The content of this file is as follows:

my_theme.info.yml

name: My Theme
type: theme
core: 8.x
base theme: thunder_admin
description: 'Extends Thunder Admin'

libraries:
  - thunder_admin/global-styling

regions:
  header: 'Header'
  pre_content: 'Pre-content'
  highlighted: Highlighted
  content: Content
  page_top: 'Page top'
  page_bottom: 'Page bottom'
  sidebar_first: 'First sidebar'
regions_hidden:
  - sidebar_first


my_theme.libraries.yml

global-styling:
  css:
    component:
      css/style.css: {}


Can any one please explain to me where I am going wrong please?
I have flushed every cache I can think of
Can any one please explain to me where I am going wrong please?

libraries:
  - thunder_admin/global-styling



There is no need to load the base theme's library, so this needs to be your theme's library. 

libraries:
  - my_theme/global-styling