The oembed iframe now has a class name to use it for stylesheets.

include/oembed.php

@@ -210,7 +210,7 @@ function oembed_iframe($src,$width,$height) {
 	$a = get_app();
 
 	$s = $a->get_baseurl()."/oembed/".base64url_encode($src);
-	return '<iframe height="' . $height . '" width="' . $width . '" src="' . $s . '" frameborder="no" >' . t('Embedded content') . '</iframe>';
+	return '<iframe class="embed_rich" height="' . $height . '" width="' . $width . '" src="' . $s . '" frameborder="no" >' . t('Embedded content') . '</iframe>';
 
 }
 

view/global.css

@@ -84,6 +84,10 @@ span.connector {
   position: relative;
 }
 
+.embed_rich {
+  display: block;
+}
+
 /* Shared Messages */
 .shared_header {
   height: 32px;