@wordpress/block-library/src/latest-posts/style.scss

.wp-block-latest-posts {
	&.alignleft {
		/*rtl:ignore*/
		margin-right: 2em;
	}
	&.alignright {
		/*rtl:ignore*/
		margin-left: 2em;
	}
	&.is-grid {
		display: flex;
		flex-wrap: wrap;
		padding: 0;
		list-style: none;

		li {
			margin: 0 16px 16px 0;
			width: 100%;
		}
	}

	@include break-small {
		@for $i from 2 through 6 {
			&.columns-#{ $i } li {
				width: calc((100% / #{ $i }) - 16px);
			}
		}
	}
}

.wp-block-latest-posts__post-date {
	display: block;
	color: $dark-gray-300;
	font-size: $default-font-size;
}