diff --git a/toolkit/themes/winstripe/mozapps/plugins/missingPlugin.css b/toolkit/themes/winstripe/mozapps/plugins/missingPlugin.css
index b31bd9369cc..4d66ecf0775 100644
--- a/toolkit/themes/winstripe/mozapps/plugins/missingPlugin.css
+++ b/toolkit/themes/winstripe/mozapps/plugins/missingPlugin.css
@@ -5,6 +5,18 @@
 
 @namespace html url(http://www.w3.org/1999/xhtml);
 
+html|object:not([width]), html|object[width=""],
+html|embed:not([width]), html|embed[width=""],
+html|applet:not([width]), html|applet[width=""] {
+  width: 240px;
+}
+
+html|object:not([height]), html|object[height=""],
+html|embed:not([height]), html|embed[height=""],
+html|applet:not([height]), html|applet[height=""] {
+  height: 200px;
+}
+
 html|object > *|*,
 html|embed > *|*,
 html|applet > *|* {