JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container-popup"></div>
	<div class="popup">
	    	<span id="close">X</span>
   
	</div>

CSS

html { 
  background: url(http://lorempixel.com/400/400) no-repeat center center fixed; 
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
}

.container-popup {
    position: relative;
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    background: rgba(0,0,0,.8);
    z-index: -1;
}

.popup {
   display:inline-block;
    background: #FFFF;
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    margin: auto;
    z-index: 1;
}
span{
	float: right;
	padding: 3px 6px;
	background-color: red;
	border-radius: 40px;
	cursor: pointer;
}

JavaScript

$(document).ready(function(){
		  $(".container-popup, #close").click(function(){
		    $('.popup').hide(); $('.container-popup').hide();
		  });
		});