diff --git a/gtk/resources/theme/Adwaita/_common.scss b/gtk/resources/theme/Adwaita/_common.scss
index ec10e46278..a35cb91a1c 100644
--- a/gtk/resources/theme/Adwaita/_common.scss
+++ b/gtk/resources/theme/Adwaita/_common.scss
@@ -932,18 +932,14 @@ GtkComboBox {
 
 .titlebar,
 .header-bar {
+  padding: 6px;
   border-width: 0 0 1px;
   border-style: solid;
   border-color: $borders_color;
   border-radius: 7px 7px 0 0;
-
   background-color: transparent;
-  background-image: linear-gradient(to bottom,
-                                    lighten($bg_color,4%),
-                                    $bg_color);
-  box-shadow: inset 0 -1px mix($borders_color, $bg_color, 30%), // bottom shade
-              inset 0 1px $top_hilight; // top highlight
-  padding: 6px;
+
+  @include headerbar_fill;
 
   &:backdrop {
     border-color: $backdrop_borders_color;
diff --git a/gtk/resources/theme/Adwaita/_drawing.scss b/gtk/resources/theme/Adwaita/_drawing.scss
index f7fa72aef5..afcfc8aab7 100644
--- a/gtk/resources/theme/Adwaita/_drawing.scss
+++ b/gtk/resources/theme/Adwaita/_drawing.scss
@@ -404,3 +404,11 @@ $widget_edge: 0 1px $borders_edge; //outer hilight "used" on
   background-image: linear-gradient(to $dir, $selected_bg_color 2px,
                                              lighten($selected_bg_color,6%));
 }
+
+@mixin headerbar_fill($c:$bg_color) {
+  background-image: linear-gradient(to bottom,
+                                    lighten($c,4%),
+                                    $c);
+  box-shadow: inset 0 -1px mix($borders_color, $c, 30%), // bottom shade
+              inset 0 1px $top_hilight; // top highlight
+}
diff --git a/gtk/resources/theme/Adwaita/gtk-contained-dark.css b/gtk/resources/theme/Adwaita/gtk-contained-dark.css
index c899cd1bd4..24e783f9a9 100644
--- a/gtk/resources/theme/Adwaita/gtk-contained-dark.css
+++ b/gtk/resources/theme/Adwaita/gtk-contained-dark.css
@@ -1156,14 +1156,14 @@ GtkComboBox {
  ***************/
 .titlebar, GtkCalendar.header,
 .header-bar {
+  padding: 6px;
   border-width: 0 0 1px;
   border-style: solid;
   border-color: #1c1f1f;
   border-radius: 7px 7px 0 0;
   background-color: transparent;
   background-image: linear-gradient(to bottom, #434a4a, #393f3f);
-  box-shadow: inset 0 -1px #303535, inset 0 1px rgba(238, 238, 236, 0.1);
-  padding: 6px; }
+  box-shadow: inset 0 -1px #303535, inset 0 1px rgba(238, 238, 236, 0.1); }
   .titlebar:backdrop, GtkCalendar.header:backdrop,
   .header-bar:backdrop {
     border-color: #1e2222;
diff --git a/gtk/resources/theme/Adwaita/gtk-contained.css b/gtk/resources/theme/Adwaita/gtk-contained.css
index 37335dfdc1..d3612d5b0c 100644
--- a/gtk/resources/theme/Adwaita/gtk-contained.css
+++ b/gtk/resources/theme/Adwaita/gtk-contained.css
@@ -1148,14 +1148,14 @@ GtkComboBox {
  ***************/
 .titlebar, GtkCalendar.header,
 .header-bar {
+  padding: 6px;
   border-width: 0 0 1px;
   border-style: solid;
   border-color: #a1a1a1;
   border-radius: 7px 7px 0 0;
   background-color: transparent;
   background-image: linear-gradient(to bottom, #f7f7f7, #ededed);
-  box-shadow: inset 0 -1px #d6d6d6, inset 0 1px white;
-  padding: 6px; }
+  box-shadow: inset 0 -1px #d6d6d6, inset 0 1px white; }
   .titlebar:backdrop, GtkCalendar.header:backdrop,
   .header-bar:backdrop {
     border-color: #a8a8a8;