simple-auction/assets/items.css

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

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