JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
  <div class="tile">
    
    When you remove this comment, the div shifts down and I do not understand what is causing that.
    <h3>This Title Moves the div down. Why?</h3>
  </div>
  <div class="tile"></div>
</div>

CSS

#container {
    position: relative;
    float: none;
    margin: 0 auto;
    border: solid blue 1px;
    width: 100%;
    text-align:center;
}

.tile {
    width: 20em;
    height: 40em;
    border:solid black 1px;
    display: inline-block;
    margin: 1.5em auto;
    vertical-align: middle;
}

h3 {
  margin: 0;
  padding: 0;
}