How to Add an Image to a CSS File. Web pages normally add images using the inline HTML "img" tag. CSS coding usually doesn't set an image's source because CSS controls design rather than content.

WordPress' built-in editor has an HTML mode that lets you override the background color of a post by changing its CSS (Cascading Style Sheet) background-color attribute to the color of your choice.

Google says images styled with CSS won’t be indexed in Image Search, advising developers to use HTML tags for important visuals.