The first commented line is your dabblet’s title

dabblet.css

/**
 * The first commented line is your dabblet’s title
 */
body {
background: #f06;
background: linear-gradient(45deg, yellow, blue);
min-height: 100%;
}
.a {
position: relative;
}
.b,.c
{
	position: absolute;
	width: 100px;
	height: 100px;
	background: red;
	transition: opacity 1s;
}
.c {
background: green;
}

.b:hover {
opacity: 1;
}
.c:hover {
visibility: hidden;
opacity: 0;
transition: visibility 1s ease 1s, opacity 1s;

}

dabblet.html

<div class="a">
<div class="b"></div>
<div class="c"></div>
</div>

dabblet.js

// alert('Hello world!');

settings.json

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