update

src/sass/gnome-shell/common/_message-list.scss

@@ -5,6 +5,7 @@
   width: if($compact == 'true', 25.5em, 31.5em);
   text-shadow: none;
   border: none;
+  padding: 0;
 
   .message-list-placeholder { spacing: $base_spacing * 2; }
 }
@@ -21,12 +22,19 @@
 
 // message bubbles
 .message {
+  margin: $base_spacing / 2 0;
+
   .popup-menu & {
     @extend %popover_bubble;
   }
 
   // icon container
   .message-icon-bin {
+    padding: $base_padding * 3;
+
+    &:ltr { padding-right: $base_padding; }
+    &:rtl { padding-left: $base_padding; }
+
     // icon size and color
     > StIcon {
       icon-size: 32px; // 32px
@@ -92,6 +100,10 @@
 .message-media-control {
   border-radius: $circular_radius;
   color: $text-secondary;
+
+  &:last-child:ltr { margin-right: $base_margin * 4; }
+  &:last-child:rtl { margin-left: $base_margin * 4; }
+
   &:hover, &:focus { color: $text; background-color: $divider; }
   &:active { color: $text; background-color: $track; }
   &:insensitive { color: $text-secondary-disabled; }
@@ -104,7 +116,7 @@
   &.fallback {
     icon-size: 32px !important;
     border: none;
-    border-radius: $menu_radius;
+    border-radius: $base_radius;
     background-color: $divider;
     color: $text-disabled;
   }

src/sass/gnome-shell/widgets-3-28/_message-list.scss

@@ -1,9 +1,3 @@
-/* Message List */
-// a.k.a. notifications in the menu
-
-.message-list {
-  padding: 0 $base_padding * 2;
-}
 
 // do-not-disturb + clear button
 .message-list-controls {
@@ -13,30 +7,16 @@
   spacing: $base_spacing * 2;
 }
 
-// message bubbles
-.message {
-  margin: $base_spacing / 2 0;
-  
-  // icon container
-  .message-icon-bin {
-    margin: 8px 0;
-    padding: 8px 0px 8px 8px;
-
-    &:rtl { padding: 8px 8px 8px 0px; }
-  }
-}
-
 .message-media-control {
-  margin: 18px $base_padding;
+  margin: $base_padding * 3 + 6px $base_padding;
   padding: $base_padding * 1.5;
-
-  &:last-child:ltr { margin-right: $base_margin * 4; }
-  &:last-child:rtl { margin-left: $base_margin * 4; }
 }
 
 // album-art
 .media-message-cover-icon {
+  padding: $base_padding;
+
   &.fallback {
-    padding: 0;
+    padding: $base_padding;
   }
 }

src/sass/gnome-shell/widgets-40-0/_message-list.scss

@@ -1,9 +1,3 @@
-/* Message List */
-// a.k.a. notifications in the menu
-
-.message-list {
-  padding: 0 $base_padding * 2;
-}
 
 // do-not-disturb + clear button
 .message-list-controls {
@@ -13,30 +7,16 @@
   spacing: $base_spacing * 2;
 }
 
-// message bubbles
-.message {
-  margin: $base_spacing / 2 0;
-  
-  // icon container
-  .message-icon-bin {
-    margin: 8px 0;
-    padding: 8px 0px 8px 8px;
-
-    &:rtl { padding: 8px 8px 8px 0px; }
-  }
-}
-
 .message-media-control {
-  margin: 18px $base_padding;
+  margin: $base_padding * 3 + 6px $base_padding;
   padding: $base_padding * 1.5;
-
-  &:last-child:ltr { margin-right: $base_margin * 4; }
-  &:last-child:rtl { margin-left: $base_margin * 4; }
 }
 
 // album-art
 .media-message-cover-icon {
+  padding: $base_padding;
+
   &.fallback {
-    padding: 0;
+    padding: $base_padding;
   }
 }

src/sass/gnome-shell/widgets-42-0/_message-list.scss

@@ -1,9 +1,3 @@
-/* Message List */
-// a.k.a. notifications in the menu
-
-.message-list {
-  padding: 0;
-}
 
 // do-not-disturb + clear button
 .message-list-controls {
@@ -16,25 +10,9 @@
   }
 }
 
-// message bubbles
-.message {
-  margin: $base_padding / 2 0;
-
-  // icon container
-  .message-icon-bin {
-    padding: ($base_padding * 3);
-
-    &:ltr {padding-right: $base_padding; }
-    &:rtl {padding-left: $base_padding; }
-  }
-}
-
 .message-media-control {
   margin: ($base_padding * 3 + 8px) $base_padding;
   padding: $base_padding * 2;
-
-  &:last-child:ltr { margin-right: $base_margin * 4; }
-  &:last-child:rtl { margin-left: $base_margin * 4; }
 }
 
 // album-art

src/sass/gtk/_common-4.0.scss

@@ -1079,6 +1079,7 @@ searchbar > revealer > box {
   border-color: $divider;
   background-color: $background;
   background-clip: border-box;
+  box-shadow: none;
 }
 
 /***************