core vertical tabs were made responsive in v1.2

The Vertical Tabs Responsive module for Drupal is no longer needed for Backdrop CMS.

Vertical tabs on content entry forms have been responsive in Backdrop since version 1.2.

Upgrade Instructions: 

If you are running the Vertical Tabs Responsive module on a Drupal 7 site:

  1. Disable and Uninstall the Vertical Tabs Responsive module from Drupal 7.
  2. Upgrade your site to Backdrop CMS.
  3. Visit any content entry form.
    1. You can confirm that vertical tabs are now responsive without the need for any additional modules.