JSFiddle - React, Tailwind, and code Playground

HTML

<div id="test"></div>
<button id="btn">Modifier le style</button>

CSS

#test{
    background-color: gold;
    width: 250px;
    height: 100px;
}

JavaScript

document.getElementById('btn').onclick = function(){
    document.getElementById('test').style.cssText += ';border: 2px solid #888; border-radius: 25px; background-color: silver;';
};