img {content: ""; background-image: url("http://placekitten.com/300/200"); width: 300px; height: 200px; display: inline-block;}
/* styling basics */
html {padding: 20px 0; background-color: #efefef;}
body {width: 80%; padding: 40px; margin: 0 auto; background: #fff; box-shadow: 1px 1px 5px rgba(0,0,0,0.5); font-family: Verdana, Arial, sans-serif; font-size: 14px;}
<img src="http://placedog.com/300/200">
<p>The image-source is deleted with CSS and replaced by a background-image. The original image is a dog :-)</p>