The first commented line is your dabblet’s title

dabblet.css

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

body {
	background: white;
	padding: 0;
	margin: 0;
}

.sep {
	z-index: -1;
	background: black;
	position: absolute;
	right: 0;
	top: 0;
	bottom: 0;
	left: 50%;
	-webkit-transition: all .5s ease-in-out;
}

.parent {
	width: 100px;
	height: 200px;
	position: absolute;
	top: 50px;
	background: red;
	cursor: pointer;
}

.maman {
	left: 100px;
}
.papa {
	right: 100px;
}
.maman:hover + .sep {
	left: 25%;
}
.papa + .sep {
	left: 
	75%;
}

dabblet.js

// alert('Hello world!');

settings.json

{"view":"split","fontsize":"100","seethrough":"","prefixfree":"1","page":"html"}