setup_theme() {
            function set_light_mode() {
                // menu theme
                document.getElementById('navigation').classList.remove('navbar-dark')
                document.getElementById('navigation').classList.add('navbar-light')
                document.getElementById("themeLight").hidden = true;
                document.getElementById("themeDark").hidden = false;
                // bootstrap related settings
                document.getElementsByTagName("html")[0].setAttribute("d