diff --git a/__tests__/_has.test.scss b/__tests__/_has.test.scss
new file mode 100644
index 0000000..57837b1
--- /dev/null
+++ b/__tests__/_has.test.scss
@@ -0,0 +1,34 @@
+@use "true" as *;
+@use "example" as *;
+@use "../src/utils/has" as *;
+
+@include test-module("`:has()` selector test [mix]") {
+  @include test("exist `:has()`") {
+    @include assert {
+      @include output {
+        @include Has {
+          @include example;
+        }
+      }
+      @include expect {
+        @supports selector(:has(a)) {
+          @include example;
+        }
+      }
+    }
+  }
+  @include test("don't exist `:has()`") {
+    @include assert {
+      @include output {
+        @include NotHas {
+          @include example;
+        }
+      }
+      @include expect {
+        @supports not selector(:has(a)) {
+          @include example;
+        }
+      }
+    }
+  }
+}
diff --git a/css/leptonChrome.css b/css/leptonChrome.css
index 1f67dd3..5a29c81 100644
--- a/css/leptonChrome.css
+++ b/css/leptonChrome.css
@@ -4637,6 +4637,12 @@
       }
     }
   }
+  @supports selector(:has(a)) {
+    #navigator-toolbox:has(#toolbar-menubar[autohide="false"]) {
+      --uc-window-drag-space-pre: 0px;
+      --uc-window-control-space: 0px;
+    }
+  }
 }
 @supports -moz-bool-pref("userChrome.tabbar.on_bottom") or -moz-bool-pref("userChrome.tabbar.one_liner") or -moz-bool-pref(
     "userChrome.hidden.tabbar"
diff --git a/src/autohide/_bookmarkbar.scss b/src/autohide/_bookmarkbar.scss
index 2c96db0..7c4b3d0 100644
--- a/src/autohide/_bookmarkbar.scss
+++ b/src/autohide/_bookmarkbar.scss
@@ -5,7 +5,7 @@
   will-change: margin-bottom, opacity;
 
   @include Option("userChrome.autohide.toolbar_overlap") {
-    @supports not selector(:has(a)) {
+    @include NotHas {
       &[collapsed="true"] {
         visibility: visible !important;
         max-height: unset !important;
diff --git a/src/autohide/_common.scss b/src/autohide/_common.scss
index 1e7c6a2..93317cb 100644
--- a/src/autohide/_common.scss
+++ b/src/autohide/_common.scss
@@ -16,7 +16,7 @@
       --uc-navbar-height: 0px;
     }
   }
-  @supports selector(:has(a)) {
+  @include Has {
     #navigator-toolbox:has(#PersonalToolbar[collapsed="true"]) {
       --uc-bm-height: 0px;
     }
diff --git a/src/leptonChrome.scss b/src/leptonChrome.scss
index 0edef2f..dc06906 100644
--- a/src/leptonChrome.scss
+++ b/src/leptonChrome.scss
@@ -6,6 +6,7 @@
 @use "utils/native_menu" as *;
 @use "utils/one_liner" as *;
 @use "utils/window_control" as *;
+@use "utils/has" as *;
 @use "utils/proton_elements" as Proton;
 @use "sass:selector";
 
diff --git a/src/tabbar/layout/_window_control_size.scss b/src/tabbar/layout/_window_control_size.scss
index d571c56..5bcb3bf 100644
--- a/src/tabbar/layout/_window_control_size.scss
+++ b/src/tabbar/layout/_window_control_size.scss
@@ -101,3 +101,10 @@
     }
   }
 }
+
+@include Has {
+  #navigator-toolbox:has(#toolbar-menubar[autohide="false"]) {
+    @include _remove_spacer_pre;
+    @include _remove_spacer_post;
+  }
+}
diff --git a/src/utils/_has.scss b/src/utils/_has.scss
new file mode 100644
index 0000000..89b8027
--- /dev/null
+++ b/src/utils/_has.scss
@@ -0,0 +1,13 @@
+// Need `:has selector`
+
+@mixin Has() {
+  @supports selector(:has(a)) {
+    @content;
+  }
+}
+
+@mixin NotHas() {
+  @supports not selector(:has(a)) {
+    @content;
+  }
+}