function startMenu() {
    document.getElementById ('toggle').addEventListener ('click', toggleMenu, false);
}

function toggleMenu() {
    var buttonElement = document.getElementById('menuIcon');

    var htmlElement = document.getElementsByTagName('html')[0];
    var logoElement = document.getElementById('sdeLogo');
    var mainElement = document.getElementsByTagName('main')[0];

    var menu = document.getElementById('menu');

    if(buttonElement.alt === '-')
    {
        htmlElement.style.backgroundColor = 'rgb(0, 120, 138)';
        logoElement.src = '/images/logos/Logo-hvid.svg';
        menu.classList.remove('d-none');
        mainElement.classList.add('d-none');

        buttonElement.alt = 'X';
    }
    else
    {
        htmlElement.style.backgroundColor = 'rgb(255, 255, 255)';
        logoElement.src = '/images/logos/Logo-normal.svg';
        menu.classList.add('d-none');
        mainElement.classList.remove('d-none');

        buttonElement.alt = '-';
    }
}