Wasn't sure the best way to submit this to you; so I'm posting here.
I've taken the "Dark" LortiUI style elements and made them compatible with your addon. It would probably be a nice addition to have a switch between "stock" and "dark", here's a link to a zip containing the *.BLP files for the dark change. Anybody reading this who wants to give them a shot, replace the *.BLP files found in
\Interface\Addons\ImprovedBlizzardUI\media
https://drive.google.com/open?id=12xQmRNl5Q7F8qRP2fllEgKRXrUSXlPDn

This is an interesting addition. I'll try this out this week.

I have a backup of these files but nonetheless will be closing this issue.