function Zweitframe(URI, Framename) {
  self[Framename].location.href = URI;
}
function gruen() {
  for (var i = 0; i < document.getElementsByTagName("body").length; i++) {
    document.getElementsByTagName("body")[i].style.backgroundImage = "url(back_gruen.png)";
  }
}
function rot() {
  for (var i = 0; i < document.getElementsByTagName("body").length; i++) {
    document.getElementsByTagName("body")[i].style.backgroundImage = "url(back_rot.png)";
  }
}
function violett() {
  for (var i = 0; i < document.getElementsByTagName("body").length; i++) {
    document.getElementsByTagName("body")[i].style.backgroundImage = "url(back_violett.png)";
  }
}
function gelb() {
  for (var i = 0; i < document.getElementsByTagName("body").length; i++) {
    document.getElementsByTagName("body")[i].style.backgroundImage = "url(back_gelb.png)";
  }
}
function grau() {
  for (var i = 0; i < document.getElementsByTagName("body").length; i++) {
    document.getElementsByTagName("body")[i].style.backgroundImage = "url(back_grau.png)";
  }
}
function blau() {
  for (var i = 0; i < document.getElementsByTagName("body").length; i++) {
    document.getElementsByTagName("body")[i].style.backgroundImage = "url(back_blau.png)";
  }
}