JSFiddle - React, Tailwind, and code Playground

HTML

<body class="test"></body>

CSS

body {
    border: 3px dotted red;
    height: 300px;
    margin: 0;
}

.test {
    margin-top: 50px !important;
}

JavaScript

setTimeout(function(){
    $('body').attr('style', 'margin-top: 0px !important');
}, 2000);