function openPopup(imgSource)
{
    var elemPopup = document.getElementById("elemPopup");
    var imgPopup = document.getElementById("imgPopup");
    var intTop = document.documentElement.scrollTop + 90;
    
    imgPopup.src = imgSource;
    
    if (elemPopup.style.visibility == "visible")
        elemPopup.style.visibility = "hidden";
    else
        elemPopup.style.visibility = "visible";
    
    elemPopup.style.top = intTop + "px";
}

function closePopup()
{
    var elemPopup = document.getElementById("elemPopup");
    elemPopup.style.visibility = "hidden";
}