JSFiddle - React, Tailwind, and code Playground

HTML

asd <br />asd <br />asd <br />asd <br />asd <br />
<button class="open">Popup</button>
<br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd<br />
<button class="open">Popup</button>
<br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />
<div style="position: relative; height: -webkit-fill-available;">
  <div id="popupholder">
    <button id="close">Close me</button>
</div>
</div>
<button class="open">Popup</button>
<br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd<br />
<button class="open">Popup</button>
<br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />asd <br />

CSS

html, body {
    margin: 0px;
}

#popupholder {
    width: 100%;
    height: 100%;
    position: absolute;
    display: box;
    display: -webkit-box;
    display: -moz-box;
    background-color: rgba(0,0,0,0.75);
    display: none;
}

#close {
    display: block;
    height: 20px;
    margin: 75px auto 0px auto;
}

JavaScript

$(document).ready(function() {
    $('.open').click(function() {
        // Block scrolling
        $('body').css('overflow', 'hidden');
        
        // Show popup
        var offset = window.pageYOffset;
        //console.log(offset);
        $('#popupholder').css({
            'display': 'block',
            'top': offset + 'px'
        });
    });
    
    $('#close').click(function() {
        // Enable scrolling
        $('body').css('overflow', 'auto');
        
        // Hide popup
        $('#popupholder').css('display', 'none');
    });
});