Help with media queries and restructuring navbar

Any ideas on how to use media queries to make the navbar that floats left on things bigger than 800px to stay to the top and not post over the content when the screen is smaller than 800px?

Hey ! I have done the exact same challenge so this is how I did it. I used flex-direction for it. https://codepen.io/ivana-zirojevic/pen/ExgjvKe