Hello
When you say 'overview' are you referring to the hover state of the menu item (:hover)??
Styling can be applied using the unique ID of your menu item. This ID can be found in the right column of your menu items list. To use simply add the following to the Custom CSS field of your templates parameters where 133 is your menu item and #FF0000 is your new menu item color (edit to taste).
#hornav > ul > li.item-133 > a:hover {
color: #FF0000 !important;
}
CiarĂ¡n