Responsive News Site Landing Page - Advice wanted

I have two parts I am struggling with...

1. On a mobile device (phone) there seems to be a bit of extra space left or right of the content as you can move the the screen left or right ever so slightly. Any idea what could be causing this?

2. I did not complete the bonus challenge of developing a functional burger menu but I did want the burger menu icon to display on mobile devices which I managed to do. However I am not able to combine it with the top nav to make both elements sticky so the navigation always appears at the top of the screen on mobile devices. What is the best way to hide and show elements such as the burger menu?