diff --git a/mozilla/layout/html/document/src/ua.css b/mozilla/layout/html/document/src/ua.css
index 9224b790aba..0214c3bbae6 100644
--- a/mozilla/layout/html/document/src/ua.css
+++ b/mozilla/layout/html/document/src/ua.css
@@ -849,16 +849,23 @@ option.selectedfocus {
 }
 
 optgroup {
+  display:block;
   font-style:italic;
   font-weight:bold;
 }
 
-optgroup > option {
+optgroup option {
+  display:block;
   padding-left:20px;
   font-style:normal;
   font-weight:normal;
 }
 
+optgroup:before {
+  display:block;
+  content:attr(label);
+}
+
 textarea {
   vertical-align: bottom;
   border: 2px inset #c0c0c0;
diff --git a/mozilla/layout/style/ua.css b/mozilla/layout/style/ua.css
index 9224b790aba..0214c3bbae6 100644
--- a/mozilla/layout/style/ua.css
+++ b/mozilla/layout/style/ua.css
@@ -849,16 +849,23 @@ option.selectedfocus {
 }
 
 optgroup {
+  display:block;
   font-style:italic;
   font-weight:bold;
 }
 
-optgroup > option {
+optgroup option {
+  display:block;
   padding-left:20px;
   font-style:normal;
   font-weight:normal;
 }
 
+optgroup:before {
+  display:block;
+  content:attr(label);
+}
+
 textarea {
   vertical-align: bottom;
   border: 2px inset #c0c0c0;