You are hiding the lists here (custom.css line 586):
ul#Contenttab1 li {display:none}
So you need to show it here in the nested ul so that the tabs are seen.
ul#Contenttab1 ul li{display:block}
You are hiding the lists here (custom.css line 586):
ul#Contenttab1 li {display:none}
So you need to show it here in the nested ul so that the tabs are seen.
ul#Contenttab1 ul li{display:block}