diff --git a/gtk/theme/Adwaita/_common.scss b/gtk/theme/Adwaita/_common.scss
index 03bd00f154..bac45c3a3c 100644
--- a/gtk/theme/Adwaita/_common.scss
+++ b/gtk/theme/Adwaita/_common.scss
@@ -4103,12 +4103,18 @@ window {
   }
 
   &.maximized,
-  &.fullscreen,
+  &.fullscreen { border-radius: 0; box-shadow: none; }
+
   &.tiled,
   &.tiled-top,
   &.tiled-left,
   &.tiled-right,
-  &.tiled-bottom { border-radius: 0; box-shadow: none; }
+  &.tiled-bottom {
+   border-radius: 0;
+   box-shadow: 0 0 0 1px $_wm_border_backdrop;
+
+   &:backdrop { box-shadow: 0 0 0 1px $_wm_border_backdrop; }
+  }
 
   &.popup { box-shadow: none; }