css/css-flexbox/flexbox_margin-auto-overflow.html

<!DOCTYPE html>
<title>flexbox | margin: auto in overflow</title>
<link rel="author" href="http://opera.com" title="Opera Software">
<link rel="help" href="http://www.w3.org/TR/css-flexbox-1/#auto-margins">
<link rel="match" href="flexbox_margin-auto-overflow-ref.html">
<style>
div {
	background: blue;
	margin: 1em 0;
	border: 1px solid black;
	height: 8em;
	width: 32em;
	position: relative;

	display: flex;
}
span {
	background: white;
	margin: 1em auto;
	width: 30em;
	display: inline-block;
	flex: 0 0 auto;
}
span+span {background: yellow;}
</style>

<div>
	<span>one</span>
	<span>two</span>
</div>