<bg-image>#, where <bg-image> is <image> or "none"
Images are drawn with the first specified one on top (closest to the user) and each subsequent image behind the previous one. Note: URLs must be in the form url("<url>") (uses double quotes), url('<url>') (uses single quotes), or url(<url>) (uses no quotes), where <url> is the URL itself.
Use CSS to include decorative images wherever possible. The CSS "background", "background-image", "content", and "list-style-image" properties can be used. This avoids additional markup in the content. Visit https://www.w3.org/TR/WCAG20-TECHS/C9 for more information.