React

CSS

body {
  background: #20262E;
  padding: 20px;
  font-family: Helvetica;
}

React

class App extends React.Component {
    componentDidMount() {
        const colorBox = ["red","blue","green"];
        const element = document.getElementById("my-div");
        setInterval(() => {
            element.style.color = colorBox[parseInt(Math.floor(Math.random() * colorBox.length))];
        }, 3000);
    }

    render() {
        return (
            <div id={"my-div"}>
                Hello, World.
            </div>
        );
    }
}

ReactDOM.render(<App />,         
    document.body.appendChild(document.createElement("div")));