<div id="result">Hello World!</div>

@keyframes color-mix {
  0% { color: red }
  100% { color: blue }
}

body {
  margin: 1em;
  width: 300px;
}

#result {
  display:flex;
  justify-content: center;
  align-items: center;
  
  height: 2rem;
  animation: color-mix 1s linear infinite alternate;
  box-shadow: 0 0 8px 0 currentColor;
  border-radius: 8px;
}