JSFiddle - React, Tailwind, and code Playground

HTML

<div class="modal">
    <div class="modal-content">
       My Modal
    </div>
</div>

CSS

.modal {
    position: absolute;
    display: block;
    top: 0;
    left: 0;
    min-width:100%;
    min-height:100%;
    background-color: #000;
    filter:alpha(opacity=50);
    -moz-opacity:0.5;
    -khtml-opacity: 0.5;
    opacity: 0.5;
    z-index: 999;
}

.modal-content {
    margin: 60px auto;
    background-image:url('http://placehold.it/700x700/fff/static/img/background-modal.jpg');
    width: 700px;
    height: 700px;
    .box-shadow(0 10px 2px #999);
}