<===> input.scss
@keyframes baz {
  0% { top: 0; bottom: 100; }
  100% { top: 100; bottom: 0; }
}
<===> output.css
@keyframes baz {
  0% {
    top: 0;
    bottom: 100;
  }
  100% {
    top: 100;
    bottom: 0;
  }
}