.mytd {
background: linear-gradient(300deg,deepskyblue,darkviolet,blue);
  background-size: 180% 180%;
  animation: gradient 3s ease infinite;
   height: 45vh;
}

@keyframes gradient {
  0% {
    background-position: 0% 50%;
  }
  50% {
    background-position: 100% 50%;
  }
  100% {
    background-position: 0% 50%;
  }
}