Pepper asked for this feature a little while ago:
<< I think it'd be great if the OP's posts were a different color (or something more distinguishable) from the other posts. That way, when OP replies to their own thread, it's easier to see their updates. This would be great for Birth in Progress, POAS, or any other thread where everyone is scrolling for updates!
For possible ideas... Reddit usernames are dark blue hyperlinks, but the OP's username is always bright blue. Maybe just the username of the OP could be changed to a bright color?
Or, maybe the font color of the post could be slightly changed for the OP? Having the post background color as a different color would work too - maybe something light but noticeable.
So we went ahead and added it! (We experimented with the colors a bit this morning, so you may have seen some variations over the past hour.) You may have to do a "hard refresh" of your browser for it to show up (usually you can do that by holding down shift while you click the refresh button).
I'll comment below so you can see it in action!