background images per page, post, content. NOT website background.

Hi,

I’m looking for a plugin that gives possibility to have a different background for each page or post. I’ve seen many that say they do, but actually only change the background of the whole site ( probably the body.)

It would be easy to make a different css-style for each page, by, for instance, using the page id number.
But I need the customers (who will maintain their website without me) to be able to do it themselves. Just with one click.

This one gives the opportunity to choose what background to change, all, page, body, post etc. Just like i I need, but has not been updated or worked on so it does not feel that safe.
https://www.lightningrank.com/how-to-add-different-background-images-to-wordpress-post-and-pages/

Any idea’s?
Thanks in advance
Margreet