Dissecting the new Windows 8 Start UI: Layers, Images and Colors oh my!
The Start UI makes use of at least three layers – a foreground (tile) layer, a background image layer, and a background color layer. Farthest from the eye is the background color layer, which is set to a single RGBA color (#0e6e39ff in this case) and fits to the dimensions of the screen. The optional middle layer contains an image used in conjunction with clever parallax scrolling to subtly hint visual depth. Floating on top are your tiles.