Responsive page with hamburguer menu and submenues.

Well, I couldn't complete this challenge completely. I wanted to target the nav to make it change when I reach the mobile version but it when I use classList it doesn't apply the class... so I had to apply it to a div inside... that made it imposible to position elements correctly. I also wanted to put the <li> down when the submenues open but I can't. They cover all the <li>