simple_forum-8.x-1.0/simple_forum.libraries.yml

simple_forum:
  version: 1.x
  css:
    theme:
      css/style.css: {}
  js:
    js/script.js: {}
  dependencies:    
    - core/jquery #Just to be safe
    - core/drupal.dialog.ajax #Required for dialogs
    - core/jquery.form #If you also want to use Ajax for form operations