var final_time = new Date();

 final_time.setFullYear(2012,5,22); // měsíc se musí dát o jeden menší
 final_time.setHours(0);
 final_time.setMinutes(0);
 final_time.setSeconds(0);
 final_time.setMilliseconds(0);


 function UpdateCounter()
 {
 
    var elm_d = document.getElementById("c_days");
    var elm_h = document.getElementById("c_hours");
    var elm_m = document.getElementById("c_minutes");
    var elm_s = document.getElementById("c_seconds");

    var now = new Date();

    var seconds_offset = Math.round((final_time.getTime()-now.getTime())/1000);
    //var offset  = (final_time.getTime()-now.getTime());

    var seconds = seconds_offset % 60;
    var minutes = Math.floor(seconds_offset / (60)) % 60;
    var hours   = Math.floor(seconds_offset / (60 * 60)) % 24;
    var days    = Math.floor(seconds_offset / (24 * 60 * 60));


    elm_d.innerHTML = days.toString();
    elm_h.innerHTML = (hours<10?"0":"")+hours.toString();
    elm_m.innerHTML = (minutes<10?"0":"")+minutes.toString();
    elm_s.innerHTML = (seconds<10?"0":"")+seconds.toString();

    setTimeout("UpdateCounter();","50");
    
    
 }

 document.onload = UpdateCounter;