$(function(){
    $("#overlay_open").toggle(function(){
        $("#overlay_open").append("<div id='blackout'></div><img id='map_large' src='img/map.png' style='position:fixed; top:50%;left:50%; display:none;margin:-250px -475px; border:1px solid #555;'>");
        $("#map_large,#blackout").fadeIn(500);
    },function(){
        $("#map_large,#blackout").fadeOut(500);
    });
});