How to add an image background to a specific form?

I need to add a background image to only one form, so can’t change the body style for the site.

In case anyone came across this issue.
My solution ended up being:
adding this element in the form:
“html”: “<img src=“” id=“bg” alt=”">\n\n",
“styleClasses”: "col-md-12 ",
“type”: “html”

and adding this CSS to the site:
#bg {
position: fixed;
top: 0;
left: 0;

/* Preserve aspet ratio */
min-width: 100%;
min-height: 100%;

If you are using TailwindCSS, see this example:

The basic idea is to ad an HTML element and fit that to the screen.,