JSFiddle - React, Tailwind, and code Playground

HTML

<body>Lorem ipsum ipsum ipsum.
    <div class="bottom-warning">This site requires an HTML rendering engine!</div>
</body>

CSS

body, html {
    margin: 0;
    padding: 0;
}
.bottom-warning {
    background-color: lightblue;
    box-sizing: border-box;
    left: 0;
    padding: 20px;
    position: fixed;
    width: 100%;
    bottom:0;
    height: auto;
    transform:translateY(100%);
    transition: transform .5s ease;
}
.bottom-warning.up {
    transform:translateY(0%);
}

JavaScript

$(document).ready(function () {
    $('.bottom-warning').addClass('up');
});