Edit in JSFiddle

var map = Gp.Map.load(
    "map", // html div
    {
         // Geoportal access key obtained here : http://professionnels.ign.fr/ign/contrats
         apiKey: "jhyvi0fgmnuxvfv0zjzorvdn",
         // layers to display
         zoom : 6,
         center : {
             x : 2.642212,
             y : 46.811339, 
             projection : "CRS:84"
         },
         layersOptions : {
             "ORTHOIMAGERY.ORTHOPHOTOS" : {},
             "GEOGRAPHICALGRIDSYSTEMS.MAPS" : {
                 opacity : 0.3
             }
         },
         // additional tools to display on the map
         controlsOptions : {
             "layerSwitcher" : {}
         
         }
    }    
) ;


var infoDiv = document.getElementById("info");
infoDiv.innerHTML = "<p> SDK version " + Gp.sdkVersion + " (" + Gp.sdkDate + ")</p>";
<div id="map"></div>
<div id="info"></div>
#map {
    padding: 5px;
    width: 100%;
    height: 600px;
    box-shadow: 0 0 10px #999;
}

#info {
    padding: 5px;
    width: 100%;
    height: 20px;
    font-family: "monospace";
    font-size: 10px;
}