<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link href="css/style.css" rel="stylesheet" type="text/css" />
<script src="js/jquery.min.js" type="text/javascript"></script>
<script>
function kodimg(){
$('ul.lol li').click(function () {
$('ul.lol li').removeClass('act');
$(this).addClass('act');
});
}
</script>
</head>
<body>
<ul class="lol">
<li id="1" class="act" onclick="kodimg(); return false;"><a href="#">объявления</a></li>
<li id="2" onclick="kodimg(); return false;"><a href="#">товары</a></li>
<li id="3" onclick="kodimg(); return false;"><a href="#">все</a></li>
</ul>
</body>
</html>