var widthtimer;
  function fixwidth() {
  
  var navDiv = document.getElementById("nav_container");
  var schatten = document.getElementById("verlauf_horizontal");
  var bilderreihe = document.getElementById("bilderreihe");
  var bildcontainer = document.getElementById("bild_container");
  var navWidth = navDiv.offsetWidth+172;
  var allWidth = document.body.clientWidth
  
  
  if (navWidth > allWidth) {
    schatten.style.width = (navWidth-172)+"px";
    bilderreihe.style.width = (navWidth)+"px";
  }
  else {
    schatten.style.width = (allWidth-172)+"px";
    bilderreihe.style.width = (allWidth)+"px";
  }

}