Navigation style of "null" parent menu item

Site is

If you take a look at the site, you'll notice the Services menu item is a different color. This is because it goes nowhere, and has three sub-menu item pages.

I want to style this so the color of the button is the same green as the others. I can get this done by "faking out" the menu item linking it to http://#, but the problem is in Safari, it actually tries to go to http://# and redirects to a page can not be found error.

I understand I can style menu items from within WordPress admin ... Appearance > Menus, but I'm not sure if I can apply a CSS Class to that menu item that already exists, or if I should create a new class and assign it to that menu item. I think the latter, but I have no idea how to do that.