var seconds = 3600;
var count_box = document.getElementById('count_box');
var in_time_input = document.getElementById('in_time');

function display(){ 
    seconds-=0.100
    if(seconds <= 0) seconds = 0;
    
    var min = Math.floor(seconds / 60);
    var sec = Math.ceil(seconds % 60);
    
    if(sec == 60){
    	min += 1;
    	sec = 0;
    }
    	 
    count_box.innerHTML = min + ' : ' + sec;
    
    if(seconds == 0){
	    if (confirm("Vypršel casový limit. Chcete vyhodnotit test?")) {
			document.cardif_test_form.submit();
		} else {
			in_time_input.value = 0;
		}
	}
    
    if(seconds > 0) {
    	setTimeout("display()",100)
    }     	
    	
} 
display();