random images using css

[msix]

I'd like the viewer to see a separate image each time the page is visited. I'm using a div id and am setting the image using the background property. I have several styles already setup called photo1, photo2, photo3, etc. that have a different background image declared in each.

HOW do I get the name generated (photo1, photo2, photo3, etc) and passed into the HTML code along the lines of <div id="photo1">?

Thanks for your time.

[Snookerman]

You can't do that with CSS, you will have to use JavaScript or PHP or some other script language.