Bootstrap sticky header navbar

by bradleytrager

HTML

<link rel="stylesheet" href="http://twitter.github.com/bootstrap/assets/css/bootstrap.css">
<div id="myCarousel" class="carousel slide">
    <ol class="carousel-indicators">
        <li data-target="#myCarousel" data-slide-to="0" class="active"></li>
        <li data-target="#myCarousel" data-slide-to="1"></li>
        <li data-target="#myCarousel" data-slide-to="2"></li>
    </ol>
    <div class="carousel-inner">
        <div class="item active">
            <img src="http://softfinity.com/img/clouds.jpg" alt="" />
            <div class="carousel-caption">
                 <h4>First Thumbnail label</h4>

                <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id
                    elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies
                    vehicula ut id elit.</p>
            </div>
        </div>
        <div class="item">
            <img src="http://softfinity.com/img/clouds.jpg" alt="" />
            <div class="carousel-caption">
                 <h4>Second Thumbnail label</h4>

                <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id
                    elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies
                    vehicula ut id elit.</p>
            </div>
        </div>
        <div class="item">
            <img src="http://softfinity.com/img/clouds.jpg" alt="" />
            <div class="carousel-caption">
                 <h4>Third Thumbnail label</h4>

                <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id
                    elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies
                    vehicula ut id elit.</p>
            </div>
        </div>
    </div> <a class="left carousel-control" href="#myCarousel" data-slide="prev">&lsaquo;</a>

    <a
    class="right carousel-control" href="#myCarousel" data-slide="next">&rsaquo;</a>
</div>
<div class="subnav...

CSS

body {
    padding: 30px;
}
section {
    padding-top: 50px;
    margin-top: -20px;
}
footer {
    margin-top: 40px;
    height: 120px;   
}

JavaScript

$(document).scroll(function(){
    var elem = $('.subnav');
    if (!elem.attr('data-top')) {
        if (elem.hasClass('navbar-fixed-top'))
            return;
         var offset = elem.offset()
        elem.attr('data-top', offset.top);
    }
    if (elem.attr('data-top') - elem.outerHeight() <= $(this).scrollTop())
        elem.addClass('navbar-fixed-top');
    else
        elem.removeClass('navbar-fixed-top');
});