main content a box, main content a supplemtal text b sidebar, supplemtal text b main content a sidebar {
  border: solid;
}
supplemtal text b sidebar {
  background: gray;
}
/********/
mammal, human {
  blood: warm;
}
mammal.furry.quadruped, human.furry.quadruped, dog.furry {
  fur: lots;
  legs: 4;
}
human {
  says: "hello";
}
dog {
  says: "woof";
}
/********/
region.country inhabitant.mouse, region.country citizen.mouse, region.country tax-payer.mouse {
  eats: cheddar;
}
region.city inhabitant.mouse, region.city region.country citizen.mouse, region.country region.city citizen.mouse, region.city tax-payer.mouse {
  eats: camembert;
}
region.country citizen {
  ssn: 123 45 6789;
}
region tax-payer {
  rate: 17%;
}
/********/
foo, .a.bar, hux {
  color: red;
}
.a.bar {
  background: gray;
}
/********/
foo, .a.bar, hux {
  color: red;
}
hux, .bar.a {
  background: blue;
}