gtk/tests/reftests/border-image-url.css

.button-image {
  engine: none;

  border-image: url("green-20x20.png") 1 stretch;

  border-width: 1px 2px 2px 1px;
  border-radius: 0;
}

.button-not-image {
  border-color: green;
  border-style: solid;
  border-width: 1px 2px 2px 1px;
  border-radius: 0;
  border-image: none;
}