http://www.w3.org/TR/css3-background/#the-border-image-width

  1. border-image-width: 100px;
  2. border-image-width: 200px;
  3. border-image-width: 50px;
  4. border-image-width: 1;
  5. border-image-width: 2;
  6. border-image-width: 0.5;
  7. border-image-width: 100%;
  8. border-image-width: 200%;
  9. border-image-width: 50%;
  10. border-image-width: 10%;
  11. border-image-width: 20%;
  12. border-image-width: 5%;