Showing and hiding Pop-up

.black_overlay{
 display: none;
 position: absolute;
 top: 0%;
 left: 0%;
 width: 100%;
 height: 100%;
 background-color: black;
 z-index:1001;
 -moz-opacity: 0.8;
 opacity:.80;
 filter: alpha(opacity=80);
}
.white_content {
 background-color: white;
 border: 5px solid #0f2c52;
 border-radius: 10px;
 display: none;
 height: 21px;
 left: 37%;
 overflow: auto;
 padding: 10px;
 position: fixed;
 text-align: center;
 top: 40%;
 width: 308px;
 z-index: 1002;
} 

Add following line of code to your JS file

function showPopUp() {
 document.getElementById('light').style.display='block';
 document.getElementById('fade').style.display='block';
}
function hidePopUp() {
 document.getElementById('light').style.display='block';
 document.getElementById('fade').style.display='block';
}

Add following line of code to your body tag