Folders behaving like pages

If I have a sub-folder, with an image (directly) inside it. I hard-code the path to it from a file with that folder, but the served page looks for the image at the root of the site, rather than the root of that folder, as expected.

I seem to be able to work around this by using <%= image_tag %>, which the outputs the path from the root of the site, but I might want to target this image as a background image. Is it possible to get folders to behave like folders?