JSFiddle - React, Tailwind, and code Playground

HTML

<div class="imgBox">
    <div class="layer">X</div>
    <img src="http://www.eronn.net/camera/test-chart/hue-saturation%20test%20chart%201.jpg" />
</div>

CSS

body {
    margin:0;
}
.imgBox img {
    width:400px;
}
.layer {
    position:absolute; top:150px;left:250px;
    width:100px;
    height:100px;
    text-align:center;
    font-size:5em;
    font-weight:bold;
    background:transparent;
    opacity:0.5;
    color:#fff; /* make transparent */
}