styling for smaller images on responsive sites. in effect at smallest (phone) screen sizes.

style.css

@media only screen and (max-width: 767px) {
	.featuredpost .alignleft, /* featured post widget */
	.featuredpost .alignright,
	img.alignright, /* standard image in content */
	img.alignleft,
	.wp-caption.alignleft, /* if you ever use smaller images with captions */
	.wp-caption.alignright {
	    display: block;
	    margin: 0 auto 24px;
	    float: none;
	}
}