לא ניתן להוסיף מחלקה חדשה לאלמנטים של דף נושא באמצעות jQuery?

Thanks for your help. Not the actual forum title I’m looking for but to display a title on hover on this little crown icon I made ( visible only for admins ):

Btw the CSS code for this is:

.names span.admin a::after {
content: "";
width: 17px;
height: 14px;
margin-left: 5px;
background-image: url(https://www.dropbox.com/s/0oi0y3ex3rtfvk5/cd-crown.svg?raw=1);
background-repeat: none;
display: inline-block;
position: relative;