JSFiddle - React, Tailwind, and code Playground

HTML

<div id="ac-wrapper" style='display:none' onClick="hideNow(event)">
    <div id="popup">
        <center>
             <h2>Popup Content Here</h2> 
            <input type="submit" name="submit" value="Submit" onClick="PopUp('hide')" />
        </center>
    </div>
</div>

CSS

#ac-wrapper {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url("images/pop-bg.png") repeat top left transparent;
    z-index: 1001;
}
#popup {
    background: none repeat scroll 0 0 #FFFFFF;
    border-radius: 18px;
    -moz-border-radius: 18px;
    -webkit-border-radius: 18px;
    height: 361px;
    margin: 5% auto;
    position: relative;
    width: 597px;
}

JavaScript

function PopUp(hideOrshow) {
        if (hideOrshow == 'hide') {
            document.getElementById('ac-wrapper').style.display = "none";
        }
        else  if(localStorage.getItem("popupWasShown") == null) {
            localStorage.setItem("popupWasShown",1);
            document.getElementById('ac-wrapper').removeAttribute('style');
        }
    }
    window.onload = function () {
        setTimeout(function () {
            PopUp('show');
        }, 0);
    }


    function hideNow(e) {
        if (e.target.id == 'ac-wrapper') document.getElementById('ac-wrapper').style.display = 'none';
    }