http://www.bootstrapmenumod.net/modules/mod_bootstrap_menu/css/bootstrapmenu.css
http://www.bootstrapmenumod.net/examples/pills/pills-with-dropdowns
<a href="#">配置<b class="caret-right"></b></a>
.navbar .dropdown-menu:after {
content: '';
display: inline-block;
border-left: 6px solid transparent;
border-right: 6px solid transparent;
border-bottom: 6px solid #ffffff;
position: absolute;
top: -6px;
left: 10px;
}
多級菜單的實現也可以參考:http://stackoverflow.com/questions/9758587/twitter-bootstrap-multilevel-dropdown-menu