Simple Overlay on btn click

HTML

<div id="overlayContainer">
    <div class="overlay">
        &nbsp;    
    </div>
    <div class="wrapperDiv">
        <div class="contentDiv">
            Overlayed!
        </div>
    </div>
</div>

<input type="button" id="testButton" value="Show Overlay"/>

CSS

#overlayContainer{
    display:none;
}
.overlay{
    background-color: #000000;
    bottom: 0;
    color: #FFFFFF;
    left: 0;
    opacity: 0.5;
    -ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=50)";
    filter: alpha(opacity=50);
    position: fixed;
    top: 0;
    width: 100%;
}
.wrapperDiv{
    position:fixed;
    top:25%;
    width:100%;
    text-align:center;
}
.contentDiv{
    background-color:#FFF;
    width:300px;
    text-align:center;
    margin:0 auto;
}

JavaScript

$(document).ready(function (){
    $("#testButton").click(function() {$('#overlayContainer').show();});
});