function einblenden (textnr) {
    bilda="bild" + textnr;
    if      (document.layers)         document.layers[bilda].visibility="visible";
    else if (document.all)            document.all[bilda].style.visibility="visible";
    else if (document.getElementById) document.getElementById(bilda).style.visibility="visible";
    else                              null;
  }

function ausblenden (textnr) {
    bilda="bild" + textnr;
    if      (document.layers)         document.layers[bilda].visibility="hidden";
    else if (document.all)            document.all[bilda].style.visibility="hidden";
    else if (document.getElementById) document.getElementById(bilda).style.visibility="hidden";
    else                              null;
  }