<div id="loading"><div></div></div>

#loading {
width:100px;
height:20px;
background:#A0DB0E;
padding:5px;
position:fixed;
left:0;
top:0;
}
#loading div {
width:1px;
height:20px;
background:#F1FF4D;
}

<script type="text/javascript">
$("#loading div").animate({width:"16px"})
</script>

<script type="text/javascript">
$("#loading").fadeOut()
</script>