Untitled

dabblet.css

body {
	background: pink
}

.popup {
	position: relative;
	width: 200px;
	height: 150px;
	padding: 10px;
	background: #fff;
	background-clip: padding-box;
	border: 5px solid rgba(0,0,0,0.5);		
}

.popup:after,
.popup:before {
	content: "";
	display:block;
	position: absolute;
	right: -12px;
	top: 11px;	
	width: 25px;
	height: 25px;
	background: #fff;	
	background-clip: padding-box;
	border: 5px solid rgba(0,0,0,0.5);		
	transform: rotate(45deg)
}
.popup:after {
	border-color: transparent;
}

.popup:before
{
	z-index: -1;
}

dabblet.html

<div class="popup">
	контент
</div>

dabblet.js

// alert('Hello world!');

settings.json

{"view":"separate","fontsize":"100","seethrough":"","prefixfree":"1","page":"all"}