function  adjustMenu(){
 var e=document.getElementById('sidenav');
 startY=150;
 vertOffset = 10;
 glide = 6;
 window.stayTopLeft = function(){
  var pY = (typeof document.body.scrollTop != 'undefined') ?  document.body.scrollTop : (typeof window.pageYOffset != 'undefined') ? window.pageYOffset : 0;
  if (pY > startY) ftlObj.y += (pY + vertOffset - ftlObj.y) / glide;
  else ftlObj.y += (startY + vertOffset - ftlObj.y) / glide;
  ftlObj.sP(ftlObj.x, ftlObj.y);
 }
 var ftlObj = document.getElementById('sidenav');
 ftlObj.sP = function(x,y) {this.style.top = y};
 ftlObj.y = startY;
 
 setInterval('stayTopLeft()',10);
}
adjustMenu();