Multiple stratified background images

[tubia]

Is your feature request related to a problem? Please describe.
Could it be possible to add the support to having multiple background images when using the background layout? For example, one could have a png image fixed at the centre (for example a boat) and the underneath an animated gif moving (for example sea waves)

Describe the solution you'd like
Add the possibility to specify more than one image in the homepage.homepage.Image config parameter

Describe alternatives you've considered
One can merge images in one and add it as the background image