diff --git a/themes/classic/editor/EditorDialog.css b/themes/classic/editor/EditorDialog.css
index 843aac01499c..c87192d846cb 100644
--- a/themes/classic/editor/EditorDialog.css
+++ b/themes/classic/editor/EditorDialog.css
@@ -137,8 +137,6 @@ tree.list {
   border: 1px inset #CCCCCC;
   /* same as in menulist.css */
   margin: 1px 5px 2px 5px;
-  width: 10em;
-  height: 3em;
   /* use rows="#" in XUL to define height */
 }
 
diff --git a/themes/modern/editor/EditorDialog.css b/themes/modern/editor/EditorDialog.css
index 4c723e9a59d8..891ae5bb6d9c 100644
--- a/themes/modern/editor/EditorDialog.css
+++ b/themes/modern/editor/EditorDialog.css
@@ -174,8 +174,6 @@ tree.list {
   /* same as in menulist.css */
   margin: 1px 5px 2px 5px;
   border: 1px inset #B4C3D4;
-  width: 10em;
-  height: 3em;
   /* use rows="#" in XUL to define height */
 }