body { padding: 100px; background:#717171; }

#slider {
	width:400px;
	overflow:hidden;
	border: 10px solid #4C4C4C;
	height:266px;
	position:relative;
	margin:auto;
}

#slider ul {
	list-style-type: none;
	margin: 0;
	padding: 0;
	position: absolute;
	top: 0;
	left: 0;
	display: flex;
}

#slider ul li img {
	display: block;
}