function otevrit(Cislo, Obj){

        if( document.getElementById('sub_' + Cislo) ){
            var block = document.getElementById('sub_' + Cislo);
            block.style.visibility = "visible";
        }

        if( Obj ){
            Obj.className = "li2";
        }
        
    }
    function zavrit(Cislo, Obj){

        if( document.getElementById('sub_' + Cislo) ){
            var block = document.getElementById('sub_' + Cislo);
            block.style.visibility = "hidden";
        }
    
        if( Obj ){
            Obj.className = "li";
        }
    }
    
    
    function prepni( blok1, blok2 ){

        var otevrit = document.getElementById(blok1);
        var zavrit = document.getElementById(blok2);


        if( zavrit && otevrit ){
            otevrit.style.display = "block";
            zavrit.style.display = "none";
        }

    }