eeeee #! is so pretty
(if that's what it is)
It is indeed #!.
Of course, it doesn't look like this by default; normally the taskbar is divided into two, to represent each workspace, and is colored a translucent black, a slightly lighter gray to represent the active workspace, and an even lighter gray to represent the active window.
In other words,

But yeah, the default settings look pretty damn good too.