update

src/sass/gnome-shell/_widgets-3-28.scss

@@ -35,7 +35,6 @@
 @import 'widgets-3-28/login-dialog';
 @import 'widgets-3-28/message-list';
 @import 'widgets-3-28/other';
-@import 'widgets-3-28/overview';
 @import 'widgets-3-28/osd';
 @import 'widgets-3-28/panel';
 @import 'widgets-3-28/popovers';

src/sass/gnome-shell/widgets-3-28/_overview.scss

@@ -1 +0,0 @@
-

src/sass/gnome-shell/widgets-40-0/_overview.scss

@@ -2,6 +2,6 @@
   spacing: $base_spacing * 2;
 }
 
-#overviewGroup {
+#overviewGroup, .controls-manager {
   background-color: $osd;
 }

src/sass/gtk/_common-3.0.scss

@@ -1902,15 +1902,14 @@ popover.background {
 }
 
 notebook {
+  background-color: $base;
+
   frame > paned > & > header,
   &.frame > header { background-color: $fill; }
 
-  &, &.frame {
-    background-color: $base;
-    border-radius: $modal-radius + $space-size;
-  }
-
   &.frame {
+    border-radius: $modal-radius + $space-size;
+
     scrolledwindow.frame {
       border: none;
     }

src/sass/gtk/apps/_gnome-3.0.scss

@@ -1522,6 +1522,7 @@ window.background { // gnome-terminal 3.32 setting
   > box.vertical > box.horizontal > stack {
     > widget > notebook.frame {
       border-width: 0;
+      border-radius: 0 0 $window-radius 0;
 
       > stack {
         border-bottom-right-radius: $window-radius;