<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN">
<html> <head>
<style type='text/css'>
.style1 {width: 300; height: 100; background: #f00000; text-align:center;}
.style2 {width: 400; height: 200; background: #00f000; text-align:left;}
</style>
</head>
<body>
<div class='group style1'>бла-бла-бла</div>
<div class='group style1'>бла-бла-бла</div>
<input type=button value='Поменять стиль'>
<script type="text/javascript" src="http://code.jquery.com/jquery-1.10.2.min.js"></script>
<script type="text/javascript">
var group = $('.group');
$(':button').click(function()
{
$(group).toggleClass('style1');
$(group).toggleClass('style2');
});
</script>
</body>
</html>