JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
     A lot of content here ...
</div>

CSS

.container {
    border: 1px solid;
}

JavaScript

$("<div>Loading...</div>").css({
    position: "absolute",
    width: "100%",
    height: "100%",
    top: 0,
    left: 0,
    background: "#ccc"
}).appendTo($(".container").css("position", "relative"));