table lines not showing in IE7?!

on my page: http://zend.warrencreative.com/wow/diary_of_events.html

there should be 1px purple lines separating the rows in the table, these are not showing in IE7

#col3 .diaryofeventsline td { border-bottom:1px solid #863c95; margin:0 15px 10px 0; } ?

thanks!