In Start11 v2, it does not seem possible to make the taskbar black, just a muted grey color. You can disable blurring, set the color to black, change the taskbar to be completely opaque, disable transparency, nothing makes it completely black. Start10 does this easily without any messing around in the settings.
The only way to make it appear black in Start11, is to set the desktop to black, disable taskbar blurring, and make it somewhat transparent. But then if any window slides behind the taskbar it makes the taskbar unreadable.
