CSS images don’t show up with bloginfo

If your style.css is in /wp-content/themes/themedirectory, and your image is at /wp-content/themes/themedirectory/images/image.jpg, then your css will be this:

background-image: url("images/image.jpg");

You can’t use php in a css file, it will not parse unless included via php (instead of with <link>).