Problem with space above header when scrolling

When scrolling, all the sections show up in that space above the header and also behind the header. How can I fix this?

Product Landing Page:

https://codepen.io/mdaw67/pen/GRKwvde?editors=1100

Remove all of the margin from your nav, and from your ul. Remember to remove the property from all of the media queries.

For the ul, write your own CSS to set the margin to 0;

Thank you so much! It worked. :+1: