diff --git a/gtk/theme/Adwaita/_common.scss b/gtk/theme/Adwaita/_common.scss
index 4833bd405f..c7f67190c8 100644
--- a/gtk/theme/Adwaita/_common.scss
+++ b/gtk/theme/Adwaita/_common.scss
@@ -1534,7 +1534,7 @@ headerbar {
   }
 }
 
-.titlebar {
+window:not(.tiled):not(.maximized) .titlebar {
   &, &:backdrop {
     border-top-left-radius: 7px;
     border-top-right-radius: 7px;
@@ -1542,10 +1542,10 @@ headerbar {
 }
 
 headerbar {
-  separator:first-child + &, // tackles the paned container case
-  &:first-child { &, &:backdrop { border-top-left-radius: 7px; }}
+  window:not(.tiled):not(.maximized) separator:first-child + &, // tackles the paned container case
+  window:not(.tiled):not(.maximized) &:first-child { &:backdrop, & { border-top-left-radius: 7px; }}
 
-  &:last-child { &, &:backdrop { border-top-right-radius: 7px; }}
+  window:not(.tiled):not(.maximized) &:last-child { &:backdrop, & { border-top-right-radius: 7px; }}
 }
 
 .titlebar:not(headerbar) {
@@ -4163,6 +4163,7 @@ decoration {
     transition: $backdrop_transition;
   }
 
+  .maximized &,
   .fullscreen &,
   .tiled & { border-radius: 0; }
 
diff --git a/gtk/theme/Adwaita/gtk-contained-dark.css b/gtk/theme/Adwaita/gtk-contained-dark.css
index 4e647dbd36..7202795c9f 100644
--- a/gtk/theme/Adwaita/gtk-contained-dark.css
+++ b/gtk/theme/Adwaita/gtk-contained-dark.css
@@ -1947,13 +1947,13 @@ headerbar button {
   margin-top: 6px;
   margin-bottom: 6px; }
 
-.titlebar, .titlebar:backdrop {
+window:not(.tiled):not(.maximized) .titlebar, window:not(.tiled):not(.maximized) .titlebar:backdrop {
   border-top-left-radius: 7px;
   border-top-right-radius: 7px; }
 
-separator:first-child + headerbar, separator:first-child + headerbar:backdrop, headerbar:first-child, headerbar:first-child:backdrop {
+window:not(.tiled):not(.maximized) separator:first-child + headerbar:backdrop, window:not(.tiled):not(.maximized) separator:first-child + headerbar, window:not(.tiled):not(.maximized) headerbar:first-child:backdrop, window:not(.tiled):not(.maximized) headerbar:first-child {
   border-top-left-radius: 7px; }
-headerbar:last-child, headerbar:last-child:backdrop {
+window:not(.tiled):not(.maximized) headerbar:last-child:backdrop, window:not(.tiled):not(.maximized) headerbar:last-child {
   border-top-right-radius: 7px; }
 
 window.csd > .titlebar:not(headerbar) {
@@ -4369,7 +4369,7 @@ decoration {
   decoration:backdrop {
     box-shadow: 0 3px 9px 1px transparent, 0 2px 6px 2px rgba(0, 0, 0, 0.2), 0 0 0 1px rgba(28, 31, 31, 0.9);
     transition: 200ms ease-out; }
-  .fullscreen decoration, .tiled decoration {
+  .maximized decoration, .fullscreen decoration, .tiled decoration {
     border-radius: 0; }
   .popup decoration {
     box-shadow: none; }
diff --git a/gtk/theme/Adwaita/gtk-contained.css b/gtk/theme/Adwaita/gtk-contained.css
index 048cd89188..aaa0aaeca5 100644
--- a/gtk/theme/Adwaita/gtk-contained.css
+++ b/gtk/theme/Adwaita/gtk-contained.css
@@ -1954,13 +1954,13 @@ headerbar button {
   margin-top: 6px;
   margin-bottom: 6px; }
 
-.titlebar, .titlebar:backdrop {
+window:not(.tiled):not(.maximized) .titlebar, window:not(.tiled):not(.maximized) .titlebar:backdrop {
   border-top-left-radius: 7px;
   border-top-right-radius: 7px; }
 
-separator:first-child + headerbar, separator:first-child + headerbar:backdrop, headerbar:first-child, headerbar:first-child:backdrop {
+window:not(.tiled):not(.maximized) separator:first-child + headerbar:backdrop, window:not(.tiled):not(.maximized) separator:first-child + headerbar, window:not(.tiled):not(.maximized) headerbar:first-child:backdrop, window:not(.tiled):not(.maximized) headerbar:first-child {
   border-top-left-radius: 7px; }
-headerbar:last-child, headerbar:last-child:backdrop {
+window:not(.tiled):not(.maximized) headerbar:last-child:backdrop, window:not(.tiled):not(.maximized) headerbar:last-child {
   border-top-right-radius: 7px; }
 
 window.csd > .titlebar:not(headerbar) {
@@ -4398,7 +4398,7 @@ decoration {
   decoration:backdrop {
     box-shadow: 0 3px 9px 1px transparent, 0 2px 6px 2px rgba(0, 0, 0, 0.2), 0 0 0 1px rgba(0, 0, 0, 0.18);
     transition: 200ms ease-out; }
-  .fullscreen decoration, .tiled decoration {
+  .maximized decoration, .fullscreen decoration, .tiled decoration {
     border-radius: 0; }
   .popup decoration {
     box-shadow: none; }