Ok, I am again confused with the terms with Node-Red.
There is a Dashboard.  On said Dashboard, there are Groups.
OK.   I can get that.
If I want to add a background picture to my dashboard, I use a template node and put something like this:
<style>
    body {
        background-image: url("/Pictures/gauges.jpg");
        background-size: cover;
    }
</style>
And set the node to:
added to site <Head> section
This adds the picture ("/Pictures/gauges.jpg") to the backdrop.
Again: Nice.
If you want to put a picture in/on to a group on that page you would do something like:
<style>
    body {
        background-image: url("/Pictures/gauges.jpg");
        background-size: cover;
    }
   #(name){
      background-image: url("/Pictures/metal_2.jpg");
    }
</style>
And that would put a picture of metal_2.jpg in side the group of name.
Again, not rocket science.
But say you have multiple Dashboards and want different pictures on each page?
Then it gets a bit tricky.
First you have to change the template node form:
added to site <Head> section to Widget in group.
Then you can start to put different pictures on different...... pages?
(What is the correct term here?)
But that comes at a cost!
You gain a 1 x 1 node which needs to be hidden somewhere on the page.
Which kind of goes against having a pattern/picture.  It will be a 1 x 1 "blank" patch.
So, what's the solution?
I don't know how to put pictures on different pages without doing that.
And I don't think that is a big ask.
(No!  Please...  Not CSS! )    
  
