Contextuel personnalisé des Boîtes en HTML, JavaScript et CSS

Voici le tutoriel vidéo pour contextuel personnalisé
https://www.youtube.com/watch?v=zK4nXa84Km4

    <!-- html file -->
    <div id="blanket" style="display:none;"></div>
    <div id="popUpDiv" style="display:none;">

        <a href="#" onclick="popup('popUpDiv')" >Click to Close CSS Pop Up</a>
    </div>  
   <a id="link" onclick="popup('popUpDiv')">Click to Open CSS Pop Up</a>

--script -------------

function toggle(div_id) {
var el = document.getElementById(div_id);
if ( el.style.display == 'none' ) { el.style.display = 'block';}
else {el.style.display = 'none';}
}
function blanket_size(popUpDivVar) {
if (typeof window.innerWidth != 'undefined') {
viewportheight = window.innerHeight;
} else {
viewportheight = document.documentElement.clientHeight;
}
if ((viewportheight > document.body.parentNode.scrollHeight) && (viewportheight > document.body.parentNode.clientHeight)) {
blanket_height = viewportheight;
} else {
if (document.body.parentNode.clientHeight > document.body.parentNode.scrollHeight) {
blanket_height = document.body.parentNode.clientHeight;
} else {
blanket_height = document.body.parentNode.scrollHeight;
}
}
var blanket = document.getElementById('blanket');
blanket.style.height = blanket_height + 'px';
var popUpDiv = document.getElementById(popUpDivVar);
popUpDiv_height=blanket_height/2-200;//200 is half popup's height
popUpDiv.style.top = popUpDiv_height + 'px';
}
function window_pos(popUpDivVar) {
if (typeof window.innerWidth != 'undefined') {
viewportwidth = window.innerHeight;
} else {
viewportwidth = document.documentElement.clientHeight;
}
if ((viewportwidth > document.body.parentNode.scrollWidth) && (viewportwidth > document.body.parentNode.clientWidth)) {
window_width = viewportwidth;
} else {
if (document.body.parentNode.clientWidth > document.body.parentNode.scrollWidth) {
window_width = document.body.parentNode.clientWidth;
} else {
window_width = document.body.parentNode.scrollWidth;
}
}
var popUpDiv = document.getElementById(popUpDivVar);
window_width=window_width/2-200;//200 is half popup's width
popUpDiv.style.left = window_width + 'px';
}
function popup(windowname) {
blanket_size(windowname);
window_pos(windowname);
toggle('blanket');
toggle(windowname);     
}

css

#blanket {
background-color:#111;
opacity: 0.65;
*background:none;
position:absolute;
z-index: 9001;
top:0px;
left:0px;
width:100%;
}
#popUpDiv {
position:absolute;
background:url(pop-back.jpg) no-repeat;
width:400px;
height:400px;
border:5px solid #000;
z-index: 9002;
}
#popUpDiv { a position:relative; top:20px; left:20px}

Contextuel Personnalisé Tutoriel