sticky sidebar scrool

<style>
.sticky {
position:fixed;
width:315px;
background:#DFE4F2;
top:1px;
z-index: 2;
}
</style>
<script type='text/javascript'>
$(document).ready(function() {
var stickyWidgetTop = $('#HTML4').offset().top;
var stickyWidget = function(){
var scrollTop = $(window).scrollTop();
if (scrollTop > stickyWidgetTop) {
$('#HTML4').addClass('sticky');
} else {
$('#HTML4').removeClass('sticky');
}
};
stickyWidget();
$(window).scroll(function() {
stickyWidget();
});
});
</script>