Add a short CSS class to an HTML Web page to use animated and stationary GIF images as the page's background. Open an HTML document and find the document's head section. Paste the following code ...

Cascading Style Sheets (CSS) level 3, also known as CSS3, introduces multiple background images support. You can list multiple background images, separating each with a comma, and set how they ...

Google's John Mueller said this morning in a webmaster hangout at the 20:55 mark that Google Image search does not index and rank images from CSS background code.