Is this possible?

[REVIVEIT]

I would like to add an image behind anything that is shown on the main page .. Its more of faded image that fills out a background.

I have added an example below! .. showing the 4 colour splats behind the main featured products.

And.. of course this image would need to scale and fit whatever size resolution it is viewed in, so that it doesn't distort the size when the resolution shrinks!

Thanks