<prompt> Construct an example of a valid CSS rule.  <response>: An example of a valid CSS rule would be:cssbody font-size: 16px; font-family: Arial, sans-serif; margin: 0; padding: 0; background-color: f1f1f1;This CSS rule is targeting the body element of an HTML document, and applying several styles to it. It sets the font size to 16 pixels, the font family to Arial or sans-serif, removes any margin or padding around the element, and sets the background color to a light gray. 