common.js

function toggleNavOpen() {
    document.querySelector("nav").classList.toggle("nav--open");
  }
function toggleNavClose() {
    document.querySelector("nav").classList.toggle("nav--open");
  }

  
document.onkeydown = function(e) {
        if (e.ctrlKey && 
            (e.keyCode === 67 || 
            e.keyCode === 86 || 
            e.keyCode === 85 || 
            e.keyCode === 117)) {
            //alert('not allowed');
            return false;
            } 
        else {
            return true;
        }
};


var prevScrollpos = window.pageYOffset;
window.onscroll = function() {
var currentScrollPos = window.pageYOffset;
if (prevScrollpos > currentScrollPos) {
	document.getElementById("navbar").style.top = "0";
} else {
	document.getElementById("navbar").style.top = "-155px";
}
prevScrollpos = currentScrollPos;
}