I'm a complete neophyte when it comes to php, so it took me months to figure this out. For those who haven't got this already, here's a solution:
<?php if (PAGE_ID == '2') { ?>
<link href="<?php echo WB_URL; ?>/styles/home.css" rel="stylesheet" type="text/css" media="screen" />
<?php } else if (PAGE_ID == '3') { ?>
<link href="<?php echo WB_URL; ?>/styles/page2.css" rel="stylesheet" type="text/css" media="screen" />
<?php } else $list = array('4', '5', '6');
if (in_array (PAGE_ID, $list)) { ?>
<link href="<?php echo WB_URL; ?>/styles/pages4to6.css" rel="stylesheet" type="text/css" media="screen" />
<?php } ?>
Page_id can be found in the web address of a given page during an edit session in WB admin (
http://yourpage.org/admin/pages/modify.php?page_id=2).