[gtk/toolbar-combobox] Don't make all buttons in toolbars flat

[Matthias Clasen <matthiasc src gnome org>]

commit 7a400da7763b2366af974620643b23c1165a1f4f
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Oct 28 21:05:13 2021 -0400

    Don't make all buttons in toolbars flat
    
    When a combobox is put in a toolbar, we don't want
    its button to lose its border.
    
    Fixes: #4384

 gtk/theme/Default/_common.scss | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/theme/Default/_common.scss b/gtk/theme/Default/_common.scss
index ebef2a800c..55f1ce23f2 100644
--- a/gtk/theme/Default/_common.scss
+++ b/gtk/theme/Default/_common.scss
@@ -895,7 +895,7 @@ modelbutton.flat arrow {
 
 /* oldstyle toolbar buttons */
 
-.toolbar button {
+.toolbar > button {
   margin: 1px;
 
    @extend %button_basic_flat;