This one below I need to log somewhere as it took me a while to find this class.
I was trying to change the background colour when hover the Site Actions drop down menu in Sharepoint 2007. In fact it’s the same colour on all drop down menus, site actions, action buttons, etc..
Here is the class in CSS :
background-color: #f1f1f1 !important; /* Roll-over on sub-menus and all drop down menus*/
border: 1px #7BA8CE solid;