This is a mod on the following page by ab-oc. I'm an end user. I Just share this change with you.
www.opencart.com/index.php?route=extension/extension/info&extension_id=18852

No support is guaranteed. Tested on 1.5.5.1, might work for other versions.

I like this mod, however, i prefer a different display style. At the same time, this mod conflict with a google snippet mod, so i changed it to be compatible.
On the other hand, admin reply will be on the right with background.