themes-wordpress/seedlet/assets/sass/components/entry/_post-thumbnail.scss

/**
 * Post Thumbnails
 */

.post-thumbnail {
	@extend %responsive-aligndefault-width;
	text-align: center;

	.singular & {
		@extend %responsive-alignfull-width-mobile;
		@extend %responsive-alignfull-width;
	}

	.post-thumbnail-inner {
		display: block;
	}
}