function hallo() {
  var schirm = "";
  if (screen.width < 800) { schirm = "min";
  } else if (screen.width >= 800 && screen.width < 1000) { schirm = "8";
  } else if (screen.width > 1000 && screen.width < 1200) { schirm = "10";
  } else { schirm = "max"; }
  schirm = schirm + screen.colorDepth;
  var bild = new Image ();
  bild.src = "screen/"+schirm+".gif";
  if (document.images) {
    document.images["reso"].src = bild.src;
} }