テンプレート:テスト2/style.css

.grainbow {
  animation: grainbow 0.3s linear infinite normal;
}
@keyframes grainbow {
  0% {background: linear-gradient(90deg, red, orange, yellow, green, blue, purple)}
  17% {background: linear-gradient(90deg, orange, yellow, green, blue, purple, red)}
  34% {background: linear-gradient(90deg, yellow, green, blue, purple, red, orange)}
  51% {background: linear-gradient(90deg, green, blue, purple, red, orange, yellow)}
  68% {background: linear-gradient(90deg, blue, purple, red, orange, yellow, green)}
  85% {background: linear-gradient(90deg, purple, red, orange, yellow, green, blue)}
  100% {background: linear-gradient(90deg, red, orange, yellow, green, blue, purple)}
}