body {
  background: linear-gradient(45deg, #202124, #642156, #202124,	#642156, #202124, #642156, #202124, #642156, #202124);
  background-size: 500%;
  animation: move_bg 120s linear 0s infinite;
}

@keyframes move_bg {
  from {
    background-position: 0% 50%;
  }
  to {
    background-position: 100% 50%;
  }
}