diff --git a/gtk/theme/Adwaita/_common.scss b/gtk/theme/Adwaita/_common.scss
index b2eb2fc47d..97b253d213 100644
--- a/gtk/theme/Adwaita/_common.scss
+++ b/gtk/theme/Adwaita/_common.scss
@@ -4598,7 +4598,9 @@ decoration {
   .popup & { box-shadow: none; }
 
   // server-side decorations as used by mutter
-  .ssd & { box-shadow: 0 0 0 1px $_wm_border; } //just doing borders, wm draws actual shadows
+  // just doing borders, wm draws actual shadows
+  .ssd & { box-shadow: 0 0 0 1px $_wm_border; }
+  .ssd &:backdrop { box-shadow: 0 0 0 1px $_wm_border_backdrop; }
 
   .csd.popup & {
     border-radius: $menu_radius;
diff --git a/gtk/theme/Adwaita/gtk-contained-dark.css b/gtk/theme/Adwaita/gtk-contained-dark.css
index 1951f82619..4b07a0da06 100644
--- a/gtk/theme/Adwaita/gtk-contained-dark.css
+++ b/gtk/theme/Adwaita/gtk-contained-dark.css
@@ -1848,6 +1848,8 @@ decoration:backdrop { box-shadow: 0 3px 9px 1px transparent, 0 2px 6px 2px rgba(
 
 .ssd decoration { box-shadow: 0 0 0 1px rgba(27, 27, 27, 0.9); }
 
+.ssd decoration:backdrop { box-shadow: 0 0 0 1px rgba(27, 27, 27, 0.9); }
+
 .csd.popup decoration { border-radius: 5px; box-shadow: 0 1px 2px rgba(0, 0, 0, 0.2), 0 0 0 1px rgba(27, 27, 27, 0.8); }
 
 tooltip.csd decoration { border-radius: 5px; box-shadow: none; }
diff --git a/gtk/theme/Adwaita/gtk-contained.css b/gtk/theme/Adwaita/gtk-contained.css
index 34ed56397a..729b1fc8f0 100644
--- a/gtk/theme/Adwaita/gtk-contained.css
+++ b/gtk/theme/Adwaita/gtk-contained.css
@@ -1864,6 +1864,8 @@ decoration:backdrop { box-shadow: 0 3px 9px 1px transparent, 0 2px 6px 2px rgba(
 
 .ssd decoration { box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.23); }
 
+.ssd decoration:backdrop { box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.18); }
+
 .csd.popup decoration { border-radius: 5px; box-shadow: 0 1px 2px rgba(0, 0, 0, 0.2), 0 0 0 1px rgba(0, 0, 0, 0.13); }
 
 tooltip.csd decoration { border-radius: 5px; box-shadow: none; }
diff --git a/gtk/theme/HighContrast/gtk-contained-inverse.css b/gtk/theme/HighContrast/gtk-contained-inverse.css
index bf27138929..c74a3df6bc 100644
--- a/gtk/theme/HighContrast/gtk-contained-inverse.css
+++ b/gtk/theme/HighContrast/gtk-contained-inverse.css
@@ -1928,6 +1928,8 @@ decoration:backdrop { box-shadow: 0 3px 9px 1px transparent, 0 2px 6px 2px rgba(
 
 .ssd decoration { box-shadow: 0 0 0 1px rgba(104, 104, 104, 0.9); }
 
+.ssd decoration:backdrop { box-shadow: 0 0 0 1px rgba(104, 104, 104, 0.9); }
+
 .csd.popup decoration { border-radius: 5px; box-shadow: 0 1px 2px rgba(0, 0, 0, 0.2), 0 0 0 1px rgba(104, 104, 104, 0.8); }
 
 tooltip.csd decoration { border-radius: 5px; box-shadow: none; }
diff --git a/gtk/theme/HighContrast/gtk-contained.css b/gtk/theme/HighContrast/gtk-contained.css
index 8592ee8d41..e0c37f5a23 100644
--- a/gtk/theme/HighContrast/gtk-contained.css
+++ b/gtk/theme/HighContrast/gtk-contained.css
@@ -1944,6 +1944,8 @@ decoration:backdrop { box-shadow: 0 3px 9px 1px transparent, 0 2px 6px 2px rgba(
 
 .ssd decoration { box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.23); }
 
+.ssd decoration:backdrop { box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.18); }
+
 .csd.popup decoration { border-radius: 5px; box-shadow: 0 1px 2px rgba(0, 0, 0, 0.2), 0 0 0 1px rgba(0, 0, 0, 0.13); }
 
 tooltip.csd decoration { border-radius: 5px; box-shadow: none; }