Theme CSS won't load in a D8 theme I'm creating a new D8 theme and am having trouble making Drupal load the CSS that is a part of my theme. I have disabled cache and am sure I'm getting the up-to-date output. 

Here's my mytheme.info.yml:

name: Mytheme
type: theme
description: 'This is a description.'
core: 8.x

libraries:
  - mytheme/global-styling

libraries-override:
  system/base: false

regions:
  header: Header
  content: Content  # the content region is required
  menu_primary: 'Menu - Primary'
  menu_secondary: 'Menu - Secondary'
  footer: Footer


Here's mytheme.libraries.yml

global-styling:
  version: 1.0
  css:
    theme:
      css/global.css: {}


and this is the top of my html.html.twig file:

&lt;!doctype html&gt;
 &lt;html lang="en"&gt;
 &lt;head&gt;
   &lt;title&gt;{{ head_title }}&lt;/title&gt;
   &lt;head-placeholder token="{{ placeholder_token|raw }}"&gt;
   &lt;css-placeholder token="{{ placeholder_token|raw }}"&gt;
   &lt;js-placeholder token="{{ placeholder_token|raw }}"&gt;
   {{ page.head }}
   {{ page.styles }}
   {{ page.scripts }}
&lt;/head&gt;
...


The content in the YAML files is not tabbed, spaces are used.

I already spent several hours trying to figure out what's wrong and why the global.css is not being linked in the header of the html page, but I have no idea. I'll be gratefull for any help.

EDIT: I found out that my CSS do load when I use this:

{{ attach_library('mytheme/global-styling') }}


but I thought the point of referring to global-styling inside mytheme.info.yml was that I don't have to do that. Did I understand that correctly?
Try this. I am using this in my base theme, and it works:

global-styling:
  version: VERSION
  css:
    base:
      css/YOURCSSFILE.css: {}