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.

He uses small background images that are places with CSS. Then, the classNames for the form elements are swithced with JavaScript. Marko also uses JavaScript to preloaded the custom images.

A background image can go a long way toward a customized Tumblr appearance. Getty Using CSS and JavaScript, you can dynamically change the background on your website.