Fixed width, fluid background

dabblet.css

/**
 * Fixed width, fluid background
 */

body { margin: 0; font-family: Futura, sans-serif; }

h1 { margin-top: 0 }

section {
	width: 700px;
	padding: 2em 9999px;
	margin: 0 -9999px;
	overflow-x: hidden;
	border: solid white;
	border-width: .1em 0;
	border-bottom-color: rgba(0,0,0,.3);
	background: url(img/noise.png) hsl(0, 40%, 70%);
	text-shadow: 0 .1em .1em white;
}

section:nth-child(3n+2) { background-color: hsl(180, 30%, 70%) }
section:nth-child(3n) { background-color: hsl(70, 40%, 70%) }

/* Debugging aids */
section,
.wrapper {
	position: relative;
	outline: 3px solid #b00;
}

section { outline-offset: -.2em }

.wrapper:before,
section:before {
	content: 'div.wrapper';
	position: absolute;
	top: 0; right: 1em;
	padding: .2em .5em;
	border-radius: 0 0 .4em .4em;
	background: #b00;
	color: white;
	text-shadow: none;
	font-size: 130%;
}


section:before {
	content: 'section';
}

dabblet.html

<section>
	<h1>Heading</h2>
	<p>Bacon ipsum dolor sit amet eiusmod laborum in aliqua. Enim nisi velit shoulder, swine tail in in fugiat esse fatback duis frankfurter nostrud proident. Swine flank nulla turducken minim aliquip beef. Et aute consectetur quis. Drumstick sausage sint beef chicken veniam short loin.</p>
</section>

<section>
	<h1>Another heading</h2>
	<p>Welsh onion fennel wakame sea lettuce kale bush tomato beetroot radicchio courgette collard greens. Horseradish peanut celtuce gumbo courgette swiss chard coriander squash garbanzo winter purslane. Courgette nori azuki bean garlic sorrel mung bean gourd soybean groundnut.</p>
	<p>Bacon ipsum dolor sit amet eiusmod laborum in aliqua. Enim nisi velit shoulder, swine tail in in fugiat esse fatback duis frankfurter nostrud proident. Swine flank nulla turducken minim aliquip beef. Et aute consectetur quis. Drumstick sausage sint beef chicken veniam short loin.</p>
</section>

<section>
	<h1>Another heading</h2>
	<p>Bacon ipsum dolor sit amet eiusmod laborum in aliqua. Enim nisi velit shoulder, swine tail in in fugiat esse fatback duis frankfurter nostrud proident. Swine flank nulla turducken minim aliquip beef. Et aute consectetur quis. Drumstick sausage sint beef chicken veniam short loin.</p>
</section>

<section>
	<h1>Another heading</h2>
	<p>Bacon ipsum dolor sit amet eiusmod laborum in aliqua. Enim nisi velit shoulder, swine tail in in fugiat esse fatback duis frankfurter nostrud proident. Swine flank nulla turducken minim aliquip beef. Et aute consectetur quis. Drumstick sausage sint beef chicken veniam short loin.</p>
</section>

<section>
	<h1>Another heading</h2>
	<p>Bacon ipsum dolor sit amet eiusmod laborum in aliqua. Enim nisi velit shoulder, swine tail in in fugiat esse fatback duis frankfurter nostrud proident. Swine flank nulla turducken minim aliquip beef. Et aute consectetur quis. Drumstick sausage sint beef chicken veniam short loin.</p>
</section>

settings.json

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

Nice one!

Though I'm pretty sure you mean debugging aides! Currently looks like something you'd get from debugging promiscuous code.