The first commented line is your dabblet’s title

dabblet.css

/**
 * The first commented line is your dabblet’s title
 */

div {
	border: 1px solid red;
	width: 300px;
	height: 300px;
	position: relative;
}

div img {
	position: absolute;
	top: 0;
	right: 0;
	bottom: 0;
	left: 0;
	margin: auto;
}

dabblet.html

<div><img src="http://img.yandex.net/i/www/logo.png" alt=""></div>

settings.json

{"view":"split-vertical","fontsize":"100","seethrough":"","prefixfree":"1","page":"all"}