text: var prevPos = window.pageYOffset;
  window.onscroll = function () {
      var currPos = window.pageYOffset;
      if (currPos == prevPos) {
          document.getElementById("navbar").style.backgroundColor = "transparent";
      }
      if (currPos - prevPos > 150) {
          document.getElementById("navbar").style.height = "100px";
          document.getElementById("navbar").style.backgroundColor =
              "rgba(0,0,0,00.85)";
      }
  };
  
  
  
  
  