JSFiddle - React, Tailwind, and code Playground

HTML

<div id="test2" class="test" style="height:30px; width:150px; background-color:red; border:1px solid green;"></div>
<button id="test1">Test</button>

CSS

div.test{
    border:2px solid black !important;
    background-color:blue !important;
}
div.test2{
    background-color:blue !important;
}

JavaScript

$('#test1').click(function(){
    $("#test2").removeClass("test").addClass("test2") 
});