JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="http://dinofly.com/scripts/jquery.magnific-popup.min.js"></script>
<link rel="stylesheet" href="http://dinofly.com/scripts/magnific-popup.css">
<div class="fixed">
  <div class="fixedTable">
    <div class="fixedCell">
      <div class="inlineBlock">
        <h2>Can't Focus On Input in Firefox</h2>
        <input type="text">
      </div>
    </div>
  </div>
</div>

 <div class="inlineBlock magnificWrapper">
        <h2>Clearfix Causing This Problem?</h2>
        <div class="wrapper">
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
           <div class="floatLeft">
           </div>
        </div>
</div>

<div class="inlineBlock">
  <h2>Cool Story BRO</h2>
</div>

CSS

.fixed{
  position: fixed;
  z-index: 2300;
  width: 100%;
  height: 100%;
 
  background-color: rgba(0,0,0,.65);
  overflow: auto;
}

.fixedTable{
   display: table;
   width: 100%;
   height: 100%;
   z-index: 2400;
}

.fixedCell{
  z-index: 2500;
  width: 100%;
  height: 100%;
  text-align: center;
  vertical-align: middle;
  display: table-cell;
}

.inlineBlock{
  position: relative;
  display: inline-block;
}

.floatLeft{
	float: left;
  width: 200px;
  height: 200px;
  background-color: yellow;
  margin: 1em;
}

.floatLeft:after {
  content: "";
  display: table;
  clear: both;
}

.absolute{
  position: absolute;
}

.overflowXHidden{
  overflow-x: hidden;
}

.mfp-container {
  text-align: center;
  position: absolute;
  width: 100%;
  height: 100%;
  left: 0;
  top: 0;
  padding: 0 8px;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box; }

JavaScript

$(document).ready(function() {
  $.magnificPopup.open({
      items: {
        src: $('.magnificWrapper'),
        type: 'inline'
      }
  });
});