JSFiddle - React, Tailwind, and code Playground

HTML

<h2>!</h2>
<button onClick="document.getElementById('pol').style.display='block'">Show</button>
<div id="pol">
I am Tanmoy Biswas

</div>

CSS

h2{margin:0 0 10px}
#pol{
    width:400px;
    height:300px;
    background:#999;
    text-align:center;
    display:none;
    margin-top:0;
    margin:10px;
}

JavaScript

window.addEventListener('mouseup',function(event){
        var pol = document.getElementById('pol');
        if(event.target != pol && event.target.parentNode != pol){
            pol.style.display = 'none';
        }
  });