function revealModal(divID)
{
    window.onscroll = function () { document.getElementById(divID).style.top = document.documentElement.scrollTop; };
    document.getElementById(divID).style.display = "block";
    document.getElementById(divID).style.top = document.documentElement.scrollTop;
}

function hideModal(divID)
{
    document.getElementById(divID).style.display = "none";
}