[x] The nav still behaves oddly on close, the menu slides over to the left. Im haven't checked how you are animating this but the nav should just be a div (if it's say 70px high) is -70px off the top of the screen and on click slides down 70px, on click out it slides back... it just need to change css top: -70px; to top: 0; then add a css transform - would this work?
This is all desktop - mobile is another task