CSS resize of image in fluid lightbox container

http://stackoverflow.com/questions/22920723/css-resize-of-image-in-fluid-lightbox-container

by Franciscolains

HTML

<div class="overlay">
    <div class="content">
        <img alt="" src="http://lorempixel.com/640/480/">
    </div>
</div>

CSS

*,
*:before,
*:after {
    -moz-box-sizing: border-box;
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
}

.overlay {
    background-color: rgba(0, 0, 0, 0.4);
    bottom: 0;
    font-size: 0;
    left: 0;
    overflow: auto;
    padding: 0 40px;
    position: absolute;
    right: 0;
    text-align: center;
    top: 0;
}

.overlay:before {
    content: '';
    display: inline-block;
    height: 100%; 
    vertical-align: middle;
}

.content {
    display: inline-block;
    margin: 20px 0;
    max-width: 100%;
    vertical-align: middle;
}

.content img {
    border: 10px solid #fff;
    display: block;
    height: auto;
    max-width: 100%;
    height:100%;
}