Zircon's navigation menu does not appear on mobile phone


I’m doing a website using drupal , i chose Zircon’s theme , did my blocks , my menu. But my menu does not appear at all on any mobile phone. Is there any fix to it? The website is : http://next.sigelec.asso.fr/ , the menu is well displayed on chrome etc.

Thanks you (sorry for my bad english)

Drupal version: 

Source: https://www.drupal.org/taxonomy/term/37/feed