.rainbow {
  background: linear-gradient(
    45deg,
    #b92d44,
    #ca9127,
    #959715,
    #0f9479,
    #0c6cb6,
    #4d40ad,
    #b92d44
  );
  background-size: 300% auto;
  background-clip: text;
  -webkit-background-clip: text;
  color: transparent;
  animation: rainbowMove 3s linear infinite;
}

@keyframes rainbowMove {
  0%   { background-position: 0% center; }
  100% { background-position: 300% center; }
}