JSFiddle - React, Tailwind, and code Playground

HTML

<div id="banner"></div>

CSS

div{
    height: 40px;
    width: 40px;
    background-color: #00BBD2;
}

div.changeColorToIndigo {
    animation-name: changeColorToIndigo;
    animation-duration: 1s;
    animation-fill-mode: forwards;
}

@keyframes changeColorToIndigo {
    from {background-color: #00BBD2;}
    to {background-color: #3F51B5;}
}

JavaScript

$(document).ready(function(){
	$('#banner').addClass('changeColorToIndigo');
})