main.js

const hamburger = document.querySelector('.header .nav-bar .nav-list .hamburger');
const mobile_menu = document.querySelector('.header .nav-bar .nav-list ul');
const menu_item = document.querySelectorAll('.header .nav-bar .nav-list ul li a');
const header = document.querySelector('.header.container');

hamburger.addEventListener('click', () => {
    hamburger.classList.toggle('active');
    mobile_menu.classList.toggle('active');
});

document.addEventListener('scroll', () => {
    var scroll_position = window.scrollY;
    if(scroll_positon > 250){
        header.style.backgroundColor = "#29323c";
    }else{
        header.style.backgroundColor = "transparent";
    }
});

    menu_item.forEach(item=>{
        item.addEventListener('click',() => {
            hamburger.classList.toggle('active');
            mobile_menu.classList.toggle('active');
        });
    });