a {
  background-image: linear-gradient(to top bottom, red 0% blue 100%);
  border-image-source: repeating-linear-gradient(to top bottom, red 0% blue 100%);
}

b {
  background-image: linear-gradient(to top left bottom, red 0% blue 100%);
  border-image-source: repeating-linear-gradient(to top left bottom, red 0% blue 100%);
}

c {
  background-image: linear-gradient(to top top, red 0% blue 100%);
  border-image-source: repeating-linear-gradient(to top top, red 0% blue 100%);
}

d {
  background-image: linear-gradient(to top to left, red 0% blue 100%);
  border-image-source: repeating-linear-gradient(to top to left, red 0% blue 100%);
}

e {
  background-image: linear-gradient(to top left 0turn, red 0% blue 100%);
  border-image-source: repeating-linear-gradient(to top left 0turn, red 0% blue 100%);
}

f {
  background-image: linear-gradient(in swishy, red 0% blue 100%);
  border-image-source: repeating-linear-gradient(in swishy, red 0% blue 100%);
}

g {
  background-image: linear-gradient(in srgb longer hue, red 0% blue 100%);
  border-image-source: repeating-linear-gradient(in srgb longer hue, red 0% blue 100%);
}

h {
  background-image: linear-gradient(in srgb in srgb, red 0% blue 100%);
  border-image-source: repeating-linear-gradient(in srgb in srgb, red 0% blue 100%);
}