~~~~~~
.rule1 {
  background-image: url(/rsrc/example.png);
}
.rule2 {
  background-image: url(/some/unknown/resource.jpg);
}
.rule3 {
  background-image: url(
    /rsrc/example.png
  );
}
~~~~~~
.rule1 {
  background-image: url(/res/hash/example.png);
}
.rule2 {
  background-image: url(/some/unknown/resource.jpg);
}
.rule3 {
  background-image: url(/res/hash/example.png);
}