Primarily. I would recommend you not to use the onclick property in HTML at all, so eventlisteners were created
document.querySelector('span#open_menu').addEventListener('click',
function(){
openNav();
})
document.querySelector('. closebtn').addEventListener('click',
function(){
closeNav();
})
-, #main div , , - .
document.querySelector('#main').addEventListener('click',
closeNav();
})
JS HTML!