index.js

function changeState(){
  let navContainer = document.querySelector('#nav-container');
  let navMenu = document.getElementById('nav-menu');
      navMenu.classList.toggle('nav-menu-open');
  let menuOpen = document.getElementById('menu-toggle');
      menuOpen.classList.toggle('menu-open');

    
    if (navMenu.classList.contains('nav-menu-open')) {
        menuOpen.setAttribute("aria-expanded", "true");
        navContainer.removeAttribute("hidden");
    } 

    if(!menuOpen.classList.contains('menu-open')){
        menuOpen.setAttribute("aria-expanded", "false");
        navContainer.setAttribute("hidden", "true");
    }
};

document.addEventListener('DOMContentLoaded', (e) => {
    let ratio = window.devicePixelRatio || 1;
    let w = screen.width * ratio;
    const navContainer = document.querySelector('#nav-container');

    if(w < 960) {
        navContainer.setAttribute("aria-hidden", "true");
    }else{
        navContainer.removeAttribute('aria-hidden')
        navContainer.removeAttribute("hidden");
    }
});