themes-wordpress/lodestar/inc/wpcom-style.css

/**
 *
 * WordPress.com specific styles for Lodestar
 *
 */

/* Jetpack related posts */

@media only screen and (max-width: 640px) {
	div#jp-relatedposts div.jp-relatedposts-items .jp-relatedposts-post {
    	width: 100%;
	}
}