I tried a few examples from the internet and neither seamed to work properly so i adapted the two that i found.
First things first:
Open your comments.php file and look for a line like this.
<li class="<?php echo $oddcomment; ?>" id="comment-< ?php comment_ID() ?>"> </li>
Second:
Simply past the following code replacing the PHP “< ?php echo $oddcomment; ?>“. Replace my@mail.com with your email that your wordpress admin account uses.
< ?php /* Only use the authorcomment class from style.css if the email is set to the admin email. */ if ($comment->comment_author_email == "my@email.com") $oddcomment = authorcomment; echo $oddcomment; ?>
Last:
Create a new css class called “.authorcomment” save your file to your theme directory and presto! Highlighted admin comments.
Enjoy!