JSFiddle - React, Tailwind, and code Playground

HTML

<h1>TEST111</h1>

CSS

body {
  animation: pulse 2s infinite;
  color: red !important;
  color: blue;
}

@keyframes pulse {
  0%, 100% {
    background: green !important;
    background: yellow;
  }
  50% {
    background: black !important;
    background: white;
  }
}