autohide bm and main toolbars: multirow compat rules use moz-bool-pref

chrome/autohide_bookmarks_and_main_toolbars.css

@@ -119,26 +119,23 @@ See the above repository for updates as well as full license text. */
     margin-top: calc(1px - var(--tab-min-height) - 2 * var(--tab-block-margin)) !important;
   }
 }
-/* Uncomment the next part to enable compatibility for multi-row_bookmarks.css
- * This would break buttons placed in the toolbar,
- * but that is likely not happening if you are using multi-row setup
- */
-
-/*
-#navigator-toolbox{ margin-bottom: var(--uc-navbar-height) !important; }
-#PersonalToolbar:not([customizing]){
-  min-height: 0 !important;
-  margin-bottom: 0;
-  height: 0;
-  overflow-y: visible !important;
-  z-index: 2;
-  padding-inline: 0 !important;
-}
-#personal-bookmarks{
-  background: inherit;
-  height: min-content;
-}
-#PlacesToolbarDropIndicatorHolder{
-  pointer-events: none !important;
+
+/* Set the following pref to enable compatibility with multi-row_bookmarks.css */
+@media (-moz-bool-pref: "userchrome.autohide-bm-and-main-toolbars.multirow-bookmarks-compat.enabled"){
+  #navigator-toolbox{ margin-bottom: var(--uc-navbar-height) !important; }
+  #PersonalToolbar:not([customizing]){
+    min-height: 0 !important;
+    margin-bottom: 0;
+    height: 0;
+    overflow-y: visible !important;
+    z-index: 2;
+    padding-inline: 0 !important;
+  }
+  #personal-bookmarks{
+    background: inherit;
+    height: min-content;
+  }
+  #PlacesToolbarDropIndicatorHolder{
+    pointer-events: none !important;
+  }
 }
-*/