Vertical centering with images and Firefox?

dabblet.css

/**
 * Vertical centering with images and Firefox?
 */

html, body { height: 100%; }

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

img {
	padding: 1em 1.5em;
	
	/* Fallback to look decent w/out Flexbox */
	max-width: 100em;
	max-height:100em;
	margin: 1em auto;
	
	width: 80px; /* This changes the height!? */
	height: 10080px; /* This changes nothing!? */
	
	/* Make it pretty */
}

dabblet.html

<img src="https://chase.sillevis.net/c.png" />

settings.json

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