var zobrazena = "druha";
function zobraz(polozka){
    if (document.getElementById){
        document.getElementById(zobrazena).style.display = "none";
        document.getElementById(polozka).style.display = "block";
        document.getElementById(zobrazena.substr(0,1)).style.backgroundColor="#fff";
        document.getElementById(polozka.substr(0,1)).style.backgroundColor="#ffd89d";
        zobrazena = polozka;
        return false;
}
    else {
        if(document.stylesheets) document.stylesheets["zalozky"].disabled = true;
        return true;
    } 
}

function preklikavani(){

    if (document.getElementById('zalozka')){
           document.getElementById('zalozka').style.visibility = "visible";
    }

    if (document.getElementById('prvni')){
           document.getElementById('prvni').style.display = "none";
    }
    if (document.getElementById('treti')){
           document.getElementById('treti').style.display = "none";
    }
    
}

 function zobrazSkryj(idecko){
    this.style.display = "none";
    el=document.getElementById(idecko).style;
    el.display=(el.display == 'block')?'none':'block';
 }