Image in html element overflow

Chrome and other browsers have overscroll (also called elastic scroll, or rubber band scroll) for the html element. (See here or here.)

I want an image in the html overscroll as an easter egg, a bit like the Slack for iOS easter egg. (See "You are up to date." in the screenshot.)

The CSS

html {
    background: green;
}

gives the overflow a color. An image does not work:

html {
    background: url(image.png);
}

How can I put an image in the html overflow?