Marta,
<!DOCTYPE HTML>
<html>
<head>
<meta charset="utf-8">
<script src="http://code.jquery.com/jquery-latest.js"></script>
<style type="text/css">
#advertising1 { padding: 2px 0px 1px 0px; }
#advertising { width: 1px; height: 1px; background:#ffcc00; }
</style>
<script type="text/javascript">
jQuery(function($)
{
function hr()
{
$('#advertising').animate({width: '100%'}, 7000, function ()
{
$(this).css({width: '1px'}); hr()
}
);
};
hr();
}
);
</script>
</head>
<body>
<div id="advertising1"><div id="advertising"></div></div>
</body>
</html>