Theme configuration in Drupal 8 has now adopted YAML. YAML is a human-friendly data serialization standard used by many programming languages, including Symfony, which Drupal 8 is now built on. With this adoption, the syntax to create an info file has now changed as well. One important concept when creating or editing any *.yml file is that proper indentation is required. Failure to properly indent configuration can lead to errors or to the configuration not loading at all. We can dive deeper into the specifics of YAML and find out more detailed information at the Symfony website (http://symfony.com/doc/current/components/yaml/yaml_format.html).