First code sample

// JS code

const menuTrigger = document.querySelector('.menu-trigger')
const menu = document.querySelector('.menu')
const mobileQuery = getComputedStyle(document.body).getPropertyValue('--phoneWidth')
const isMobile = () => window.matchMedia(mobileQuery).matches
const isMobileMenu = () => {
  menuTrigger.classList.toggle('hidden', !isMobile())
  menu.classList.toggle('hidden', isMobile())
}

isMobileMenu()

menuTrigger.addEventListener('click', () => menu.classList.toggle('hidden'))

window.addEventListener('resize', isMobileMenu)