white stroke and transparent fill

.outline {
  color: white;
  text-shadow: -1px -1px 0 #000, 1px -1px 0 #000, -1px 1px 0 #000, 1px 1px 0 #000;
}


@supports ((text-stroke: 2px black) or (-webkit-text-stroke: 2px black)) {
  .outline {
    color: transparent;
    -webkit-text-stroke: 2px white;
    text-stroke: 2px black;
    text-shadow: none;
  }
}