text:   // open and close dropdown menu
    window.onclick = function(event) {
        var dropdowns = document.getElementsByClassName("dropdown-content");
        var i;
        for (i = 0; i < dropdowns.length; i++) {
            let openDropdown = dropdowns[i];
            if (openDropdown.classList.contains('show')) {
                openDropdown.classList.remove('show');
            }
        }
        if (event.target.matches('.dropbtn')) {
            let openDropdown = event.target.nextElementSibling;
            if (!openDropdown.classList.contains('show')) {
                openDropdown.classList.add('show');
            }
        }
    }