.bypostauthor doesn't contain the actual post

I have a problem trying to style my author comments, and the problem is that the class bypostauthor doesn’t seem to contain the actual post, but rather be a separate list item underneath the post.

Example from my source code:

<div class="commentpost"><div style="color:red;">
<p>The one on FM-Base isn’t the latest one. I re-saved the database from the Editor, and replaced the file on this site. It should work now. =)</p>
</div>
<p class="thdrpy">[<a href="javascript:void(0)" onclick="movecfm(event,17,1,'mantralux');">Reply</a>]</p></div>

<div class="clear"></div>
<li class="comment byuser comment-author-mantralux bypostauthor odd alt thread-odd thread-alt depth-1" id="comment-17"></li>
</div>
</li>

I’m using a slightly modified version of the Equilibrium theme.

Is there any way I can change the behaviour to have the .bypostauthor class be the post wrapper instead of a div beneath the content?

This is the website: https://www.mantralux.com/the-arsenal-simulation-compendium/

The end result should be that the white comment boxes in the comment section should be editable, I’d like to have another background color for the div containing the author comments.

Any takers? ??