JSFiddle - React, Tailwind, and code Playground

HTML

<div id="tekst1">Hallo Wereld.</div>

CSS

body{
font-family: sans-serif;
}
#tekst1{
    background-color: rgb(255,0,0);
}

JavaScript

var block=document.getElementById("tekst1");
block.style.width='150px';
block.innerHTML = "test";