Improve navs tabs on small screens
This is a common missing feature from Bootstrap.
Many solutions exist:
https://stackoverflow.com/questions/13888598/create-responsive-tabs-using-bootstrap-they-should-get-stacked-automatically-on
https://github.com/flatlogic/bootstrap-tabcollapse
https://stackoverflow.com/questions/22032136/how-to-disable-stacking-of-bootstrap-justified-tabs-on-small-screens