Only show an image once as background when rendering a pdf from wkhtmltopdf

Question

I'm trying to get a single image to be set as watermark when using wkhtmltopdf. If I use background-repeat: no-repeat, nothing shows.

I've tried creating the image to be an A4 size (landscape 1056 by 768) but this just "walks" down the page. Below the CSS I tried for the a4 sized image.

    body {
           background: url('http://localhost/someimage.png');
           background-repeat: repeat-y ;
           background-position: center;
           background-size: 100%;
    }

Anything else I can do?