function zeige_normalansicht() {
    document.getElementById("intro_layer").style.display      = "none"; // durch display: none kann man auch nicht mehr draufklicken
    document.getElementById("wrapper").style.opacity          = 1;
    document.getElementById("wrapper").style.Mozopacity       = 1;
    document.getElementById("wrapper").style.Khtmlopacity     = 1;
    document.getElementById("wrapper").style.filter           = "alpha(opacity=100)";
}

function lese_cookie() {
    a = document.cookie;
    cookiename = a.substr(0,a.search('='));
    cookiewert = a.substr(a.search('=')+1,a.search(';'));
    if(cookiewert == '') { cookiewert = a.substr(a.search('=')+1,a.length); }
    return(cookiewert); 
}

function setze_cookie() {    
    /*
    var expires = new Date();
    expires = new Date(expires.getTime() +1000*60*60*24);
    document.cookie = 'rae-lichte=intro_gezeigt; expires=' + expires.toGMTString() + ';';
    */
    document.cookie = 'rae-lichte=intro_gezeigt';
}
    
function opacity_aendern(deckkraft) {
    deckkraft_faktor = (deckkraft / 100);
    document.getElementById("intro_layer").style.opacity      = (deckkraft_faktor);
    document.getElementById("intro_layer").style.MozOpacity   = (deckkraft_faktor);
    document.getElementById("intro_layer").style.KhtmlOpacity = (deckkraft_faktor);
    document.getElementById("intro_layer").style.filter       = "alpha(opacity=" + deckkraft + ")";
    document.getElementById("wrapper").style.opacity          = (1-deckkraft_faktor);
    document.getElementById("wrapper").style.Mozopacity       = (1-deckkraft_faktor);
    document.getElementById("wrapper").style.Khtmlopacity     = (1-deckkraft_faktor);
    document.getElementById("wrapper").style.filter           = "alpha(opacity=" + 100-deckkraft + ")";    
    // alert ("deckkraft: "+deckkraft_faktor);
    if (deckkraft_faktor <= 0 ) { zeige_normalansicht(); }
}

function intro_ausblenden() {
    
    var speed = 10;
    var timer = 0;
    for(i = 100; i >= 0; i--) {
        setTimeout("opacity_aendern(" + i + ")",(timer * speed));
        timer++;
    }    
}

function start_intro(wartezeit) {    
    
    document.getElementById("toppi").style.display = "block";    
    var cookie_content = lese_cookie();     
    
    if (cookie_content == "intro_gezeigt") {
        zeige_normalansicht();    
    }
    
    if (cookie_content != "intro_gezeigt") {
        setze_cookie(); // gleich das cookie setzen
        document.getElementById("intro_layer").style.opacity          = 1;
        document.getElementById("intro_layer").style.Mozopacity       = 1;
        document.getElementById("intro_layer").style.Khtmlopacity     = 1;
        document.getElementById("intro_layer").style.filter           = "alpha(opacity=100)";                          
        setTimeout("intro_ausblenden()",wartezeit); 
    }   
}