JSFiddle - React, Tailwind, and code Playground

HTML

<div id="header">Test</div>
<div id="header">yest</div>

JavaScript

$(document).ready(function() {
    var colors = ["#385c78", "#9d302f"],
    selectedColor = colors[Math.floor(Math.random()*colors.length)]
    header = $("div#header");
    
    header.css("background-color", selectedColor);
});