#imported-file {
  background-image: url("http://example.com/assets/css/folder/relative/path");
  background-image: url("http://example.com/assets/css/relative/path");
  background-image: url("http://example.com/assets/relative/path");
  background-image: url("module");
  background-image: url("module/path");
  background-image: url("module/relative/path");
}
#rootpath-rewrite-urls-local {
  background-image: url("http://example.com/assets/css/relative/path");
  background-image: url("http://example.com/assets/relative/path");
  background-image: url("http://example.com/assets/css/path");
  background-image: url("http://example.com/assets/css");
  background-image: url("module");
  background-image: url("module/path");
  background-image: url("module/relative/path");
}