Most of the files are

  /* Copyright 2019 brain-tec AG (Brig, Switzerland, http://www.braintec-group.com)
  :Copyright: This stylesheet has been placed in the public domain.
  Copyright 2015 Antiun Ingenieria S.L. - Javier Iniesta
  Copyright 2015 Antiun Ingeniería S.L. - Antonio Espinosa
  Copyright 2015 Tecnativa - Antonio Espinosa
  Copyright 2015-2016 Jairo Llopis <jairo.llopis@tecnativa.com>
  Copyright 2015-2018 Tecnativa - Jairo Llopis
  Copyright 2016 - Ursa Information Systems <http://ursainfosystems.com>
  Copyright 2016 Jairo Llopis <jairo.llopis@tecnativa.com>
  Copyright 2016 Pedro M. Baeza <pedro.baeza@tecnativa.com>
  Copyright 2016 Tecnativa - Pedro M. Baeza
  Copyright 2018 Tecnativa - Jairo Llopis
  Copyright 2019 brain-tec AG - Olivier Jossen
  Copyright 2018 Flectra Community

Many files also contain contributions from third
parties. In this case the original copyright of
the contributions can be traced through the
history of the source version control system.

When that is not the case, the files contain a prominent
notice stating the original copyright and applicable
license, or come with their own dedicated COPYRIGHT
and/or LICENSE file.