body {
    background: #fff;
}

.photo-list {
	display: -webkit-flex;
	display: flex;
	flex-wrap: wrap;
	margin-right: -5px;
	margin-bottom: -5px;
}

.photo-item {
	width: 25%;
	padding-right: 5px;
	padding-bottom: 5px;
}

.photo-cover {
	padding-top: 100%;
}

.photo-cover .cover-wrap {
	position: absolute;
	top: 0;
	left: 0;
	width: 100%;
	height: 100%;
}