Greenshift has many Background options, but sometimes you need very specific behavior. So, this is the way how to turn any block to be the background for other blocks.
And it’s quite easy. Simply, drop your block inside the parent block, then use the Advanced tab – Position in the parent block to set it as a relative position. In the child block, which you want to have as background, use the next parameters for Position
in case you want to add content over the background. Add another container or block and set its position as Relative, then, set z-index to more than 0.