var layerOld = null
function layerOpen(layer){
    if(layerOld!=null){
        document.getElementById(layerOld).style.display = "none";
        document.getElementById("link"+layerOld).className = "";
    }
    document.getElementById(layer).style.display = "block";
    document.getElementById("link"+layer).className = "active";
    layerOld=layer;
}