JSFiddle - React, Tailwind, and code Playground

HTML

<div id="front">Front</div>
<div id="back">Back</div>
<div id="log">Log:<BR/></div>

CSS

#front {
    z-index:10;
    border:1px solid black;
    padding:5px;
    height:100px;
    width:100px;
    position:absolute;
    left:60px;
    top:30px;
    background-color:#123456;
    color:white;
}

#back {
    z-index:100;
    border:1px solid black;
    padding:5px;
    height:100px;
    width:100px;
    position:absolute;
    left:10px;
    top:10px;
    background-color:#DDDDDD;
    color:black;
}

#log {
   position:absolute;
   top:145px;
   left:10px;
   border:1px solid black;
   width:300px;
   height:300px;
   padding:5px;
   background-color:#EEEEEE;
   color:black; 
}

JavaScript

var mouseX = 0;
var mouseY = 0;
var front = 0;
var back = 0;

function log(text) {
    $("#log").append(text + '<BR>');
}

document.getElementById('front').addEventListener('click', () => {
	log('click front');
})

document.getElementById('back').addEventListener('click', () => {
	log('click back');
})