JSFiddle - React, Tailwind, and code Playground

HTML

<div class="group">
    <div class="container">container</div>
    <div id="loading-img"></div>
    <button id="button">Submit</button>
</div>

CSS

#loading-img {
	background: url("http://www.chimply.com/images/samples/classic-spinner/animatedEllipse.gif") center center no-repeat;
    display: none;
    height: 100px;
    width: 100px;
    position: absolute;
    top: 33%;
    left: 1%;
    right: 1%;
    margin: auto;
}
.container{
    height: 300px;
    background: #000;
    color: #fff;
}
.group {
    position: relative;
    width: 100%;
}

JavaScript

$("#button").click(function() {
    $(".container").css("opacity", 0.2);
   $("#loading-img").css({"display": "block"});
});