Адаптивные изображения

CSS:

.img-responsive {
	display: block;
	height: auto;
	max-width: 100%;
}

functions.php:

// images auto class
function add_image_responsive_class($content) {
   global $post;
   $pattern ="/<img(.*?)class=\"(.*?)\"(.*?)>/i";
   $replacement = '<img$1class="$2 img-responsive"$3>';
   $content = preg_replace($pattern, $replacement, $content);
   return $content;
}
add_filter('the_content', 'add_image_responsive_class');