simple-auction/assets/items.css

.items {
	margin: -1rem;
}
.item {
	margin: 1rem;
}

.item {
	position: relative;
}
.item:after {
	content: '';
	display: block;
	width: 100%;
	padding-top: calc(10 / 16 * 100%);
}
.item a {
	display: block;
	position: absolute;
	top: 0;
}


@media (min-width: 768px) {
	.items {
		display: flex;
		flex-wrap: wrap;
	}
	.item {
		flex: 1 0 auto;
		width: calc(50% - 4rem);
	}

	.item:after {
		padding-top: calc(4 / 3 * 100%);
	}
}