Desktop picture: Yawning Void
This is a desktop picture for Macs running at 1366 by 768, such as the 11-inch MacBook Air:
No, it’s not pure black. Yes, that bar at the top is part of it.
It’s meant to be used at that resolution and no other, with menu-bar translucency turned on. Scaling it, especially vertically, will make it look wrong.
If you want to adapt it to a different size, here’s the original document, editable in Lineform. You should scale the document and the background to the desired screen size, and the menu-bar background to the desired width.