This works! Are you trying to get rid of the checkbox? If so, try this after your breakpoint:

/* Getting rid of the checkbox's view */
nav input[type='checkbox'], nav label {
  display: none;
}

I am currently developing my ePortfoli; and I noticed that the checkbox was in view for a larger breakpoint than what I was working on for my @media query (max width 320); and it works fine. I am still developing my site for mobile responsiveness; so you will be able to see the difference of where I applied that code in certain breakpoints vs not applying it in others to hide my checkbox used for my hamburger menu (which proves the code works!). You can check out my site and use Google Chrome Developer Tools: https://scn.ninja/

I even proved and something about this in my repository: https://github.com/supercodingninja/ePortfolio/blob/main/style.css