Drupal uses .yml files for dealing with libraries (css and js), this is great. But the setup of those files in your theme isn’t exactly intuitive, but it’s not hard either.

In this tutorial you will learn how to register your theme and add css and JavaScript files to your theme.

Code used in this video

endymion.info.yml

name: Endymion
description: Drupal 8 Starter Theme
type: theme
core: 8.x
libraries:
 - endymion/global-css
 - endymion/global-js
stylesheets-remove:
 - core/themes/stable/css/views/views.module.css
 - core/themes/stable/css/system/components/align.module.css
```**endymion.libraries.yml**

```yml 
global-css:
 css:
   theme:
     css/style.css: {}

global-js:
 js:
   js/main.js: {}
 dependencies:
   - core/jquery