For this project, I migrated thousands of nodes of content from an old Drupal 7 site with a non-responsive theme into a Drupal 8 installation. This made use of Acquia's Lightning distribution, and a new responsive theme was built from scratch using the Designer's mockups.
Below is an example twig template from this project. It's for the magazine story nodes.
One issue with Drupal 8 is that the Title field is no longer one that may be rearranged from the content type field display settings, and is only available as a Block.
To create a layout where the title of a node displays below, for example, a header image, or author information, a custom template may be built.