After I active Bootstrap to my theme I am developing in Wordpress - my nevmenu disappeared. It is there when I scale the website down (max widt 980px) and is visible as a collapse menu. Maybe there is some .nav styling from Bootstrap that are conflicting with my theme. 

Can you please help me finding out what it is?

Here is a link to the website: <http://list.thorsteinnhelgason.is/index.php/2018/02/15/prufupostur/>
Best B