Creating a responsive menu system for a site with a lot of content
for creating responsive menu you have lots of projects 

below are some 

https://www.drupal.org/project/responsive_menus

https://www.drupal.org/project/responsive_navigation

https://www.drupal.org/project/responsive_dropdown_menus

https://www.drupal.org/project/responsive_menu

try any one will help you out.