rework navigator-toolbox-background selectors

chrome/autohide_bookmarks_and_main_toolbars.css

@@ -88,13 +88,13 @@ See the above repository for updates as well as full license text. */
 :where(#titlebar,#tab-notification-deck,.global-notificationbox){
   -moz-box-ordinal-group: 0;
 }
-:root[BookmarksToolbarOverlapsBrowser] #navigator-toolbox-background{
-  margin-bottom: 0 !important;
+:root[BookmarksToolbarOverlapsBrowser] #navigator-toolbox{
+  margin-bottom: calc(-1px - var(--uc-bm-height) + var(--uc-navbar-height)) !important;
   z-index: auto !important;
 }
 /* Show when cursor is over popups/context-menus - cannot control which ones */
 /*
-#mainPopupSet:hover ~ box > toolbox > .browser-toolbar{
+#mainPopupSet:hover ~ toolbox > .browser-toolbar{
   transition-delay: 100ms !important;
   transform: rotateX(0);
 }

chrome/autohide_toolbox.css

@@ -37,7 +37,7 @@ See the above repository for updates as well as full license text. */
 }
 
 
-/* #mainPopupSet:hover ~ box > toolbox, */
+/* #mainPopupSet:hover ~ toolbox, */
 /* Uncomment the above line to make toolbar visible if some popup is hovered */
 #navigator-toolbox:hover,
 #navigator-toolbox:focus-within{

chrome/multi-row_tabs_below_content.css

@@ -41,12 +41,9 @@ See the above repository for updates as well as full license text. */
   :root[uidensity="compact"]{ --multirow-toolbar-height: 34px }
   :root{ border-top-width: 0px !important }
 
-  #navigator-toolbox-background{
+  #navigator-toolbox{
     -moz-box-ordinal-group: 2; /* Fx <112 compatibility */
     order: 2;
-    border-bottom: 0px !important;
-  }
-  #navigator-toolbox{
     border-bottom: none !important;
   }
   /* Re-order window and tab notification boxes */
@@ -232,7 +229,7 @@ See the above repository for updates as well as full license text. */
     top: calc(var(--multirow-toolbar-height) + var(--multirow-top-padding));
     width: 100vw;
   }
-  :root[BookmarksToolbarOverlapsBrowser] #navigator-toolbox-background{
+  :root[BookmarksToolbarOverlapsBrowser] #navigator-toolbox{
     margin-bottom: 0 !important;
     z-index: auto !important;
   }

chrome/toolbars_below_content.css

@@ -63,7 +63,7 @@ See the above repository for updates as well as full license text. */
   #main-window > body > box{ margin-top: 0 !important; }
   #toolbar-menubar{ z-index: 1; background-color: var(--lwt-accent-color,black); }
   
-  :root[BookmarksToolbarOverlapsBrowser] #navigator-toolbox-background{
+  :root[BookmarksToolbarOverlapsBrowser] #navigator-toolbox{
     margin-block: calc(-1 * var(--bookmarks-toolbar-height)) 0 !important;
   }
   :root[BookmarksToolbarOverlapsBrowser] .newTabBrowserPanel{