JSFiddle - React, Tailwind, and code Playground

HTML

<body class="gray">
    <header>
        <div>Test</div>
    </header>
    <button>Click</button>
</body>

CSS

.gray {
    background: #ddd;
}
.yellow {
    background: yellow;
}
header {
    display: block;
    border: 1px solid;
}
button {
    margin: 10px 0;
}

JavaScript

$(function() {
    $('button').on('click', function() {
        $('header').toggle();
        $('body').toggleClass('yellow');
    });
});