theme style.css is not loading for custom theme
Try adjusting your spacing. 2 spaces are required.

.info.yml:

name: contra
description: 'Drupal 8 starter theme'
type: theme
core: 8.x
libraries:
  - contra/global-styling


.libraries.yml:

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


Also, take a look at https://www.drupal.org/docs/8/theming/adding-stylesheets-css-and-javascript-js-to-a-drupal-8-theme