First of all, thank you for reading this.
Problem
I wonder if there exists a way to create some kind of 3d website background, for instance from a SVG file and some CSS codes ? More precisely, is it possible to set some layers of a SVG background to be in front of the html body elements ? Since it is not possible to use z-index in SVG file, I wonder if there exist a workaround to achieve this.
Example
To give you a concrete example, I would really appreciate to do this on a SEO consultant website. For this specific example, how can I force the clouds (at the bottom of the background image) to be in foreground so that the text and every body elements appear from behind the cloud (including the sidebar) ?
Illustrations: Current display vs. Desired display
Notes
(1) Currently the format is jpg (& webp), since I encountered compatibility issues with macOS devices and SVG background. Moreover, I'm not sure that using SVG as website background is a good idea.
(2) I initially tried to add the clouds as a separate image in a specific div but then I could not figure out how to apply identical responsive setting as the ones of the background img (set by the theme I'm using).
I'd be very grateful for any advice or idea you may have.
Thank you. :)