html,body{height:100%;background:linear-gradient(270deg,red,orange,#ff0,green,#00f,indigo,violet,red);background-size:300%;animation:roll 5s linear infinite}.app-root{display:flex;flex-direction:column;justify-content:flex-start;align-items:center}@keyframes roll{0%{background-position:0%}to{background-position:100%}}