Okay, suppose you wish to add some CSS to your admins' usernames...in your "additional.css" template(s), you could add:
HTML Code:
.usm_admin {
font-weight: bold;
color: #ff0000;
}
Note: The above is just an example of CSS...you can have as much as you want there.
And then in the first HTML markup field, put:
Code:
<span class="usm_admin">
And in the second field: