Adding a Superscript to submenu/page on a Navigation Bar Dropdown

Hi, 

I am trying to add superscript to one of the submenus/ pages  under a navigation  bar page link  but i am unable to do so. 

I found this code on the user forum but it only adds the superscript to a parent item on Navigation bar but i would like to a superscript to one of the child item in the Nav Bar . How can i do that ?

div.header-nav-item:nth-child(3) a:after {
    content: "NEW";
    font-size: 10px;
    position: relative;
    top: -10px;
}

Any help would be greatly appreciated. 

Hi. What is your site url? We can check easier