document.addEventListener(“DOMContentLoaded”, function() {

var scrollLock = false;

let runOnScroll = function(evt) {
  if(!scrollLock) {
    scrollLock = true;
    let img = document.getElementById("headerImg");
    img.style.filter = "blur("+0.05*window.scrollY+"px)";
    let header = document.getElementById("header");
    header.style.backgroundColor = "rgba(04,09,17,"+0.003*window.scrollY+")";
    scrollLock = false;
  }
}

window.addEventListener("scroll",runOnScroll);

});