Which addon is the cause of the transparent borders and related edge-matching of all your various buttonl/chat/unit frames there?
The panels behind my actionbars and chatwindows are created with Eepanels. I set the eepanels to a black, semi-transparent color.
The border was achieved by creating my own tooltip border and placing it in my Interface folder, allowing any addon using Blizzard's standard Tooltip border, to be using my custom Tooltip Border.