function revealModal(divID){
    window.onscroll = function () { document.getElementById(divID).style.top = document.body.scrollTop; };
    document.getElementById(divID).style.display = "block";
    document.getElementById(divID).style.top = document.body.scrollTop;
}
function hideModal(divID){
    document.getElementById(divID).style.display = "none";
}