Resize height of dynamiaclly sized div based on window size
<p>I have a div that is acting as a mask at the top of my page. The content of the page itself is absolutely centered on the page (see css). I give the div .holder a height based on the distance the #nav div is from the top of the window using jQuery.</p>

<p>CSS:</p>

<pre><code>#pagewrap 
{
    position:absolute;
    width:915px;
    margin-left:-458px;
    padding:0;
    left:50%;
    height:100%;
    margin-top:-330px;
    top:50%;
}

.holder 
{
    background: none repeat scroll 0 0 black;
    height: 0;
    position: fixed;
    top: 0;
    width: 915px;
    z-index: 10000;
}

#nav 
{
    position:fixed;
    text-align:center;
    width:915px;
    height:224px;
    margin:0 auto;
    background:url(nav-off.png) no-repeat scroll 0 0 transparent;
    z-index:1001;
    font-family:'Cabin',sans-serif;
}
</code></pre>

<p>Javascript:</p>

<pre><code>var t = $("#nav");
var offset = t.offset();
$(function() 
{
    $(".holder").css("height" , offset.top);
});
</code></pre>

<p>Simple enough, but if the size of the window changes I'd like to have the height updated.</p>
