Margin Width

Margin with %.

by shriek

HTML

<blockquote>
	<p>
		Here's to the crazy ones. The misfits. The rebels. The troublemakers. The round pegs in the square holes. The ones who see things differently. They're not fond of rules. And they have no respect for the status quo. You can quote them, disagree with them, glorify or vilify them. About the only thing you can't do is ignore them. Because they change things. They push the human race forward. And while some may see them as the crazy ones, we see genius. Because the people who are crazy enough to think they can change the world, are the ones who do.
	</p>
	<footer>
		<cite><a href="http://en.wikipedia.org/wiki/Think_Different#Text" title="Think Different, an advertising slogan for Apple Inc.">Apple Inc.</a></cite>
	</footer>
</blockquote>

<blockquote>
	<p>
		I made so many mistakes in running the company so far, basically any mistake you can think of I probably made. I think, if anything, the Facebook story is a great example of how if you're building a product that people love you can make a lot of mistakes
	</p>
	<footer>
		<cite><a href="http://www.bbc.co.uk/blogs/thereporters/maggieshiels/2010/11/mark_zuckerberg_ive_made_so_many_mistakes.html" title="Mark Zuckerberg: I've made so many mistakes">Mark Zuckerberg, Facebook Inc.</a></cite>
	</footer>
</blockquote>

CSS

blockquote {
	position: relative;
	margin-bottom: 40px;
}
	blockquote:after {
	    content: '';
		position: absolute;
		width: 50%;
		left: 25%;
		bottom: -20px;
		border-bottom: 1px solid #666;
	}