Navigation Dropdowns Behind Content DIV

I have the code posted on my codepen. What I am trying to do is move the yellow content box behind the navigation links. I have two different navigation bars. One for mobile and one for desktop. When clicking the drop down menu on both desktop and mobile they appear to be behind the content DIV. I have tried a few things with no luck. This site is experimental but I am just stuck. Any help would be much appreciated. if you need anymore information just ask. Thank You..

https://codepen.io/bigstrib/pen/jObEaKd

{`enter code here`}