diff --git a/src/sass/gtk/_common-3.0.scss b/src/sass/gtk/_common-3.0.scss
index 26173a91..9e148b42 100644
--- a/src/sass/gtk/_common-3.0.scss
+++ b/src/sass/gtk/_common-3.0.scss
@@ -2396,6 +2396,24 @@ cursor-handle {
   }
 }
 
+%monterey_tab {
+  color: $disabled_fg_color;
+  background-color: transparentize($base_color, 1);
+  border: none;
+  transition: all 150ms ease-out;
+  padding: 0 0;
+
+  &:hover:not(:checked) {
+    color: mix($fg_color, $disabled_fg_color, 50%);
+    background-color: rgba($fg_color, 0.06);
+  }
+
+  &:checked {
+    color: $fg_color;
+    background-color: rgba($fg_color, 0.12);
+  }
+}
+
 notebook {
   padding: 0;
 
@@ -2410,62 +2428,81 @@ notebook {
   }
 
   > header {
-    padding: 0;
-    background-color: darken($header_bg, 10%);
+    @if $monterey == 'false' {
+      background-color: darken($header_bg, 10%);
 
-    // Set box-shadow to make the header frame color more easy to see
-    // Set margin to hide the ugly borders around the header
-    &.top {
-      margin-top: -1px;
-      box-shadow: inset 0 1px $solid_borders_color, inset 0 -1px $borders_color;
-      @if $variant=='light' {
-          box-shadow: inset 0 1px $borders_color,
-                      inset 0 -1px $borders_color,
-                            1px 0 $borders_color,
-                            -1px 0 $borders_color;
+      // Set box-shadow to make the header frame color more easy to see
+      // Set margin to hide the ugly borders around the header
+      &.top {
+        box-shadow: inset 0 1px $solid_borders_color, inset 0 -1px $solid_borders_color;
+        @if $variant=='light' {
+            box-shadow: inset 0 1px $solid_borders_color,
+                        inset 0 -1px $solid_borders_color,
+                              1px 0 $solid_borders_color,
+                              -1px 0 $solid_borders_color;
+        }
       }
-    }
 
-    &.bottom {
-      box-shadow: inset 0 1px $borders_color, inset 0 -1px $solid_borders_color;
-      @if $variant=='light' {
-          box-shadow: inset 0 1px $borders_color,
-                      inset 0 -1px $borders_color,
-                      1px 0 $borders_color,
-                      -1px 0 $borders_color;
+      &.bottom {
+        box-shadow: inset 0 1px $solid_borders_color, inset 0 -1px $solid_borders_color;
+        @if $variant=='light' {
+            box-shadow: inset 0 1px $solid_borders_color,
+                        inset 0 -1px $solid_borders_color,
+                        1px 0 $solid_borders_color,
+                        -1px 0 $solid_borders_color;
+        }
       }
-      margin-bottom: -1px;
-    }
 
-    &.right {
-      box-shadow: inset 1px 0 $borders_color, inset -1px 0 $solid_borders_color;
-      @if $variant=='light' {
-          box-shadow: inset 1px 0 $borders_color,
-                      inset -1px 0 $borders_color,
-                      0 1px $borders_color,
-                      0 -1px $borders_color;
+      &.right {
+        box-shadow: inset 1px 0 $solid_borders_color, inset -1px 0 $solid_borders_color;
+        @if $variant=='light' {
+            box-shadow: inset 1px 0 $solid_borders_color,
+                        inset -1px 0 $solid_borders_color,
+                        0 1px $solid_borders_color,
+                        0 -1px $solid_borders_color;
+        }
       }
-      margin-right: -1px;
-    }
 
-    &.left {
-      box-shadow: inset 1px 0 $solid_borders_color, inset -1px 0 $borders_color;
-      @if $variant=='light' {
-          box-shadow: inset 1px 0 $borders_color,
-                      inset -1px 0 $borders_color,
-                      0 1px $borders_color,
-                      0 -1px $borders_color;
+      &.left {
+        box-shadow: inset 1px 0 $solid_borders_color, inset -1px 0 $solid_borders_color;
+        @if $variant=='light' {
+            box-shadow: inset 1px 0 $solid_borders_color,
+                        inset -1px 0 $solid_borders_color,
+                        0 1px $solid_borders_color,
+                        0 -1px $solid_borders_color;
+        }
+      }
+    } @else {
+      &.top {
+        border-bottom: 1px solid $borders_color;
+      }
+
+      &.bottom {
+        border-top: 1px solid $borders_color;
+      }
+
+      &.right {
+        border-left: 1px solid $borders_color;
+      }
+
+      &.left {
+        border-right: 1px solid $borders_color;
       }
-      margin-left: -1px;
     }
 
     button.flat.toggle.popup {
       min-width: $menuitem_size;
-      border-radius: 0;
-      padding: 0;
       border: none;
       box-shadow: none;
-      margin: 0;
+
+      @if $monterey == 'false' {
+        border-radius: 0;
+        padding: 0;
+        margin: 0;
+      } @else {
+        margin-left: $container_padding / 2;
+        border-radius: $bt_radius;
+      }
 
       &:active, &:checked {
         color: $fg_color;
@@ -2476,19 +2513,34 @@ notebook {
     @each $_pos, $_bpos in (top, bottom), (bottom, top), (right, left), (left, right) {
       // sizing and borders
       &.#{$_pos} {
-        padding: 0;
+        @if $monterey == 'false' {
+          margin-#{$_pos}: -1px;
+          padding: 0;
+        } @else {
+          padding: $container_padding / 2;
+        }
 
         > tabs > tab {
           padding: $container_padding - 4px $container_padding + 4px;
+          outline-offset: -4px;
           min-width: 24px;
           min-height: 24px;
-          border-radius: 0;
-          outline-offset: -4px;
 
-          // tab overlap
-          + tab {
-            @if $_pos==top or $_pos==bottom { margin-left: -1px; }
-            @else { margin-top: -1px; }
+          @if $monterey == 'false' {
+            border-radius: 0;
+
+            // tab overlap
+            + tab {
+              @if $_pos==top or $_pos==bottom { margin-left: -1px; }
+              @else { margin-top: -1px; }
+            }
+          } @else {
+            border-radius: $bt_radius;
+
+            + tab {
+              @if $_pos==top or $_pos==bottom { margin-left: $container_padding / 2; }
+              @else { margin-top: $container_padding / 2; }
+            }
           }
         }
       }
@@ -2527,24 +2579,30 @@ notebook {
       &:disabled { color: transparentize($disabled_fg_color,0.3); }
     }
 
-    &.top,
-    &.bottom {
-      > tabs > tab {
-        &:first-child { border-left: none; }
-        &:last-child { border-right: none; }
+    @if $monterey == 'false' {
+      &.top,
+      &.bottom {
+        > tabs > tab {
+          &:first-child { border-left: none; }
+          &:last-child { border-right: none; }
+        }
       }
-    }
 
-    &.left,
-    &.right {
-      > tabs > tab {
-        &:first-child { border-top: none; }
-        &:last-child { border-bottom: none; }
+      &.left,
+      &.right {
+        > tabs > tab {
+          &:first-child { border-top: none; }
+          &:last-child { border-bottom: none; }
+        }
       }
     }
 
     > tabs > tab {
-      @extend %tabs_tab;
+      @if $monterey == 'false' {
+        @extend %tabs_tab;
+      } @else {
+        @extend %monterey_tab;
+      }
 
       // close button
       button.flat, button.close-button {
diff --git a/src/sass/gtk/apps/_gnome-3.22.scss b/src/sass/gtk/apps/_gnome-3.22.scss
index eb8f57ae..e76a29bd 100644
--- a/src/sass/gtk/apps/_gnome-3.22.scss
+++ b/src/sass/gtk/apps/_gnome-3.22.scss
@@ -337,12 +337,14 @@ $nautilus_sidebar_image: image($dark_sidebar_bg);
   }
 
   notebook {
-    margin-left: -1px;
-    margin-right: -1px;
-
     &.background.csd { background-color: transparent; }
 
-    tab { margin-left: -1px; }
+    @if $monterey == 'false' {
+      margin-left: -1px;
+      margin-right: -1px;
+
+      tab { margin-left: -1px; }
+    }
 
     scrolledwindow {
       .view:not(:hover):not(:active):not(:selected) {
@@ -595,8 +597,16 @@ terminal-window {
     button.flat.toggle.popup {
       min-height: 28px;
       min-width: 28px;
-      margin: -2px;
+      padding: 0;
+
+      @if $monterey == 'false' {
+        margin: -2px;
+      } @else {
+        margin: -2px 0;
+      }
     }
+
+    tab { padding: 0 0; }
   }
 
   &.background.csd.maximized { border-radius: 0 0 0 0; } // Fixed gnome 3.32 issue: Unable to restore window size after maximization