hover animation for height:auto

/**
 * transition using width or height auto
 */
ul,li {
	display: block;
	margin: 0;
	padding: 0;
	width: 250px;
}
li {
	border-bottom: 1px solid lightgrey;
}
li > ul {
	max-height: 0;
	overflow: hidden;
	text-indent: .5em;
	transition: max-height 1s;
}
li:hover > ul {
	max-height: 1000px;
}