Vertical centering with Flexbox + margin fallback

dabblet.css

/**
 * Vertical centering with Flexbox + margin fallback
 * Lea Verou & David Storey
 */

html, body { height: 100%; }

body {
	width: 100%; /* needed for FF */
	margin: 0;
	
	/* Flexbox hawtness */
	display: flex;
	align-items: center;
}

div {
	padding: 1em 1.5em;
	
	/* Fallback to look decent w/out Flexbox */
	max-width: 10em;
	margin: 1em auto;
	
	/* Make it pretty */
	background: slategray;
	text-align: center;
	border-radius: .3em;
	color: #405060;
	font: bold 150% sans-serif;
	text-shadow: 0 2px 1px hsla(0,0%,100%,.2);
}

dabblet.html

<div>OMG, I’m centered!</div>

settings.json

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

This example is following the new flex-box syntax in the spec, right? How widespread is support for this? Might html5please.us need updating, dare I wonder? :D

It includes both syntaxes.

Is not centered in chromioum

Try This:
Give this CSS to the div which you have to centralize..

.class-name {
        margin: 0px;
	padding:0px;
	float: left;
	width:100%;
	position:absolute;
	top: 50%;
	transform: translateY(-50%) translateX(-50%);
	left:50%;
}