button {
  background: transparent;
  color: #fff;
  font-size: 17px;
  text-transform: uppercase;
  font-weight: 600;
  border: none;
  padding: 20px 30px;
  perspective: 30rem;
  border-radius: 10px;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.308);
}

button::before {
  content: '';
  display: block;
  position: absolute;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  border-radius: 10px;
  background: linear-gradient(320deg, rgba(0, 140, 255, 0.678), rgba(128, 0, 128, 0.308));
  z-index: 1;
  transition: background 3s;
}

button:hover::before {
  animation: rotate 1s infinite;
  transition: all .5s;
}

@keyframes rotate {
  0% {
    transform: rotateY(180deg);
  }

  100% {
    transform: rotateY(360deg);
  }
}