The first commented line is your dabblet’s title

dabblet.css

/**
 * The first commented line is your dabblet’s title
 */
body {
background: #fff;

min-height: 100%;}
div {
float: left
}

.left {
	background: #fff;
	border-style:solid;
	border-width:20px 20px 200px 0px;
	border-color: transparent #000 #000 transparent;
	width:0;
	height:0;
}


.right {
	background: #fff;
	border-style:solid;
	border-width:200px 0 20px 20px;
	border-color: #000 transparent transparent #000;
	width:0;
	height:0;
}
.middle {
	background: #000;
	height: 220px;
	width: 700px;
}

dabblet.html

<div class='left'></div>
<div class='middle'></div>
<div class='right'></div>

settings.json

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