JSFiddle - React, Tailwind, and code Playground

HTML

<div id="processing" class="modal fade">
    <div class="modal-dialog" style="max-width: 350px">
        <div class="modal-content">
            <div class="panel-heading modal-header dialog-header">
                <h4 class="modal-title">Please Wait...</h4>
            </div>
            <div class="modal-body">
                <img src="http://media.jumpingjack.com/JumpingJack/loading.gif" class="img-responsive" />
            </div>
        </div>
    </div>
</div>

CSS

.modal-body {
    position:relative; /* This avoids image to go off the container */
    height: 250px;
    border: 1px solid #ff0000;
}
.img-responsive {
    width:50px;
    height: 50px;
    position:absolute;
    left:50%;
    top:50%;
    margin-top:-25px;
    margin-left:-25px;
}
#processing{ 
    width:300px;
    height: 300px;
    border:1px solid #000;
    padding:15px;
    margin:0 auto;
}