Opera hack

dabblet.css

/**
 * Opera hack
 */
.body {
	background: lightgray;
	height: 200px;
}
/* .opera-only - is dummy selector */
.opera-only :-o-prefocus,
.body {
	background: yellow;
}

.highlight {
	font-weight: bold;
}

dabblet.html

<div class="body">Yellow background in <span class="highlight">Opera</span> and light gray in other browsers</div>

dabblet.js

// alert('Hello world!');

settings.json

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