<html>
<head>
<style>
.odd {
height: 5px;
background: #960;
}
.even {
height: 5px;
background: #09C;
}
</style>
<script src="js/jquery-1.7.1.min.js"></script>
<script type="text/javascript">
$(document).ready(function() {
$('div:odd').addClass('odd');
$('div:even').addClass('even');
})
</script>
</head>
<body>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
</body>
<html>