diff --git a/css/leptonChrome.css b/css/leptonChrome.css
index eb412a78..947d8567 100644
--- a/css/leptonChrome.css
+++ b/css/leptonChrome.css
@@ -5530,21 +5530,26 @@
           :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
             visibility: collapse !important;
           }
-          :root[tabsintitlebar] #titlebar,
-          :root[tabsintitlebar] #toolbar-menubar,
-          :root[tabsintitlebar] #TabsToolbar {
+          :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+          :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+          :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
             z-index: 1;
           }
-          :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-          :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-          :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+          :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+          :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+          :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
             opacity: 1 !important;
           }
-          :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-          :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-          :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+          :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+          :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+          :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
             opacity: var(--inactive-titlebar-opacity);
           }
+          @supports not -moz-bool-pref("userChrome.tabbar.on_bottom") {
+            :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+              display: flex !important;
+            }
+          }
         }
         /* At Activated Menubar */
         :root:not([chromehidden~="menubar"], [sizemode="fullscreen"])
@@ -5689,21 +5694,26 @@
             :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
               visibility: collapse !important;
             }
-            :root[tabsintitlebar] #titlebar,
-            :root[tabsintitlebar] #toolbar-menubar,
-            :root[tabsintitlebar] #TabsToolbar {
+            :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+            :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+            :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
               z-index: 1;
             }
-            :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-            :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-            :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+            :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+            :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+            :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
               opacity: 1 !important;
             }
-            :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-            :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-            :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+            :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+            :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+            :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
               opacity: var(--inactive-titlebar-opacity);
             }
+            @supports not -moz-bool-pref("userChrome.tabbar.on_bottom") {
+              :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+                display: flex !important;
+              }
+            }
           }
           /* At Activated Menubar */
           :root:not([chromehidden~="menubar"], [sizemode="fullscreen"])
@@ -5845,21 +5855,26 @@
             :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
               visibility: collapse !important;
             }
-            :root[tabsintitlebar] #titlebar,
-            :root[tabsintitlebar] #toolbar-menubar,
-            :root[tabsintitlebar] #TabsToolbar {
+            :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+            :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+            :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
               z-index: 1;
             }
-            :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-            :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-            :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+            :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+            :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+            :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
               opacity: 1 !important;
             }
-            :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-            :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-            :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+            :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+            :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+            :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
               opacity: var(--inactive-titlebar-opacity);
             }
+            @supports not -moz-bool-pref("userChrome.tabbar.on_bottom") {
+              :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+                display: flex !important;
+              }
+            }
           }
           /* At Activated Menubar */
           :root:not([chromehidden~="menubar"], [sizemode="fullscreen"])
@@ -6019,21 +6034,26 @@
               :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
                 visibility: collapse !important;
               }
-              :root[tabsintitlebar] #titlebar,
-              :root[tabsintitlebar] #toolbar-menubar,
-              :root[tabsintitlebar] #TabsToolbar {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
                 z-index: 1;
               }
-              :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-              :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-              :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
                 opacity: 1 !important;
               }
-              :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-              :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-              :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
                 opacity: var(--inactive-titlebar-opacity);
               }
+              @supports not -moz-bool-pref("userChrome.tabbar.on_bottom") {
+                :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+                  display: flex !important;
+                }
+              }
             }
           }
           @media screen and (max-width: 1100px) {
@@ -6182,21 +6202,26 @@
               :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
                 visibility: collapse !important;
               }
-              :root[tabsintitlebar] #titlebar,
-              :root[tabsintitlebar] #toolbar-menubar,
-              :root[tabsintitlebar] #TabsToolbar {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
                 z-index: 1;
               }
-              :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-              :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-              :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
                 opacity: 1 !important;
               }
-              :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-              :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-              :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
                 opacity: var(--inactive-titlebar-opacity);
               }
+              @supports not -moz-bool-pref("userChrome.tabbar.on_bottom") {
+                :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+                  display: flex !important;
+                }
+              }
             }
             /* At Activated Menubar */
             :root:not([chromehidden~="menubar"], [sizemode="fullscreen"])
@@ -6340,21 +6365,26 @@
               :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
                 visibility: collapse !important;
               }
-              :root[tabsintitlebar] #titlebar,
-              :root[tabsintitlebar] #toolbar-menubar,
-              :root[tabsintitlebar] #TabsToolbar {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
                 z-index: 1;
               }
-              :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-              :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-              :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
                 opacity: 1 !important;
               }
-              :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-              :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-              :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
                 opacity: var(--inactive-titlebar-opacity);
               }
+              @supports not -moz-bool-pref("userChrome.tabbar.on_bottom") {
+                :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+                  display: flex !important;
+                }
+              }
             }
             /* At Activated Menubar */
             :root:not([chromehidden~="menubar"], [sizemode="fullscreen"])
@@ -19873,22 +19903,32 @@
   :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
     visibility: collapse !important;
   }
-  :root[tabsintitlebar] #titlebar,
-  :root[tabsintitlebar] #toolbar-menubar,
-  :root[tabsintitlebar] #TabsToolbar {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
     z-index: 1;
   }
-  :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-  :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-  :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
     opacity: 1 !important;
   }
-  :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-  :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-  :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
     opacity: var(--inactive-titlebar-opacity);
   }
 }
+@media (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (not (-moz-bool-pref: "userChrome.tabbar.one_liner")) and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (not (-moz-bool-pref: "userChrome.tabbar.one_liner")) and (-moz-bool-pref: "userChrome.hidden.tabbar") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (not (-moz-bool-pref: "userChrome.tabbar.one_liner")) and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (not (-moz-bool-pref: "userChrome.tabbar.one_liner")) and (-moz-bool-pref: "userChrome.hidden.tabbar") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (not (-moz-bool-pref: "userChrome.tabbar.one_liner")) and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (not (-moz-bool-pref: "userChrome.tabbar.one_liner")) and (-moz-bool-pref: "userChrome.hidden.tabbar") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")) {
+  :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+    display: flex !important;
+  }
+}
 @media (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (not (-moz-bool-pref: "userChrome.tabbar.one_liner")) and (-moz-bool-pref: "userChrome.tabbar.on_bottom"),
   (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (not (-moz-bool-pref: "userChrome.tabbar.one_liner")) and (-moz-bool-pref: "userChrome.hidden.tabbar"),
   (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (not (-moz-bool-pref: "userChrome.tabbar.one_liner")) and (-moz-bool-pref: "userChrome.tabbar.on_bottom"),
@@ -20079,22 +20119,29 @@
   :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
     visibility: collapse !important;
   }
-  :root[tabsintitlebar] #titlebar,
-  :root[tabsintitlebar] #toolbar-menubar,
-  :root[tabsintitlebar] #TabsToolbar {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
     z-index: 1;
   }
-  :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-  :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-  :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
     opacity: 1 !important;
   }
-  :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-  :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-  :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
     opacity: var(--inactive-titlebar-opacity);
   }
 }
+@media (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive")) and (-moz-bool-pref: "userChrome.tabbar.one_liner.tabbar_first") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive")) and (-moz-bool-pref: "userChrome.tabbar.one_liner.tabbar_first") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive")) and (-moz-bool-pref: "userChrome.tabbar.one_liner.tabbar_first") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")) {
+  :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+    display: flex !important;
+  }
+}
 @media (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive")) and (-moz-bool-pref: "userChrome.tabbar.one_liner.tabbar_first"),
   (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive")) and (-moz-bool-pref: "userChrome.tabbar.one_liner.tabbar_first"),
   (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive")) and (-moz-bool-pref: "userChrome.tabbar.one_liner.tabbar_first") {
@@ -20279,22 +20326,29 @@
   :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
     visibility: collapse !important;
   }
-  :root[tabsintitlebar] #titlebar,
-  :root[tabsintitlebar] #toolbar-menubar,
-  :root[tabsintitlebar] #TabsToolbar {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
     z-index: 1;
   }
-  :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-  :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-  :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
     opacity: 1 !important;
   }
-  :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-  :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-  :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
     opacity: var(--inactive-titlebar-opacity);
   }
 }
+@media (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive")) and (-moz-bool-pref: "layout.css.osx-font-smoothing.enabled") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive")) and (-moz-bool-pref: "layout.css.osx-font-smoothing.enabled") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive")) and (-moz-bool-pref: "layout.css.osx-font-smoothing.enabled") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")) {
+  :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+    display: flex !important;
+  }
+}
 @media (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive")) and (-moz-bool-pref: "layout.css.osx-font-smoothing.enabled"),
   (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive")) and (-moz-bool-pref: "layout.css.osx-font-smoothing.enabled"),
   (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive")) and (-moz-bool-pref: "layout.css.osx-font-smoothing.enabled") {
@@ -20533,22 +20587,32 @@
   :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
     visibility: collapse !important;
   }
-  :root[tabsintitlebar] #titlebar,
-  :root[tabsintitlebar] #toolbar-menubar,
-  :root[tabsintitlebar] #TabsToolbar {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
     z-index: 1;
   }
-  :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-  :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-  :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
     opacity: 1 !important;
   }
-  :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-  :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-  :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
     opacity: var(--inactive-titlebar-opacity);
   }
 }
+@media screen and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (max-width: 1100px) and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  screen and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (max-width: 1100px) and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  screen and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (max-width: 1100px) and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  screen and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (max-width: 1100px) and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  screen and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (max-width: 1100px) and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  screen and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (max-width: 1100px) and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")) {
+  :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+    display: flex !important;
+  }
+}
 @media screen and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (max-width: 1100px),
   screen and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (max-width: 1100px),
   screen and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (max-width: 1100px),
@@ -20739,22 +20803,29 @@
   :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
     visibility: collapse !important;
   }
-  :root[tabsintitlebar] #titlebar,
-  :root[tabsintitlebar] #toolbar-menubar,
-  :root[tabsintitlebar] #TabsToolbar {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
     z-index: 1;
   }
-  :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-  :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-  :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
     opacity: 1 !important;
   }
-  :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-  :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-  :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
     opacity: var(--inactive-titlebar-opacity);
   }
 }
+@media screen and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (min-width: 1100px) and (-moz-bool-pref: "userChrome.tabbar.one_liner.tabbar_first") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  screen and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (min-width: 1100px) and (-moz-bool-pref: "userChrome.tabbar.one_liner.tabbar_first") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  screen and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (min-width: 1100px) and (-moz-bool-pref: "userChrome.tabbar.one_liner.tabbar_first") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")) {
+  :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+    display: flex !important;
+  }
+}
 @media screen and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (min-width: 1100px) and (-moz-bool-pref: "userChrome.tabbar.one_liner.tabbar_first"),
   screen and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (min-width: 1100px) and (-moz-bool-pref: "userChrome.tabbar.one_liner.tabbar_first"),
   screen and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (min-width: 1100px) and (-moz-bool-pref: "userChrome.tabbar.one_liner.tabbar_first") {
@@ -20939,22 +21010,29 @@
   :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
     visibility: collapse !important;
   }
-  :root[tabsintitlebar] #titlebar,
-  :root[tabsintitlebar] #toolbar-menubar,
-  :root[tabsintitlebar] #TabsToolbar {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
     z-index: 1;
   }
-  :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-  :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-  :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
     opacity: 1 !important;
   }
-  :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-  :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-  :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+  :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+  :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+  :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
     opacity: var(--inactive-titlebar-opacity);
   }
 }
+@media screen and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (min-width: 1100px) and (-moz-bool-pref: "layout.css.osx-font-smoothing.enabled") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  screen and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (min-width: 1100px) and (-moz-bool-pref: "layout.css.osx-font-smoothing.enabled") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")),
+  screen and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (min-width: 1100px) and (-moz-bool-pref: "layout.css.osx-font-smoothing.enabled") and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.tabbar.on_bottom")) {
+  :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+    display: flex !important;
+  }
+}
 @media screen and (-moz-bool-pref: "userChrome.tabbar.on_bottom") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (min-width: 1100px) and (-moz-bool-pref: "layout.css.osx-font-smoothing.enabled"),
   screen and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (min-width: 1100px) and (-moz-bool-pref: "layout.css.osx-font-smoothing.enabled"),
   screen and (-moz-bool-pref: "userChrome.hidden.tabbar") and (not (-moz-bool-pref: "userChrome.hidden.titlebar_container")) and (-moz-bool-pref: "userChrome.tabbar.one_liner") and (-moz-bool-pref: "userChrome.tabbar.one_liner.responsive") and (min-width: 1100px) and (-moz-bool-pref: "layout.css.osx-font-smoothing.enabled") {
diff --git a/css/leptonChromeESR.css b/css/leptonChromeESR.css
index 2c97af55..2783f849 100644
--- a/css/leptonChromeESR.css
+++ b/css/leptonChromeESR.css
@@ -5918,21 +5918,26 @@
           :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
             visibility: collapse !important;
           }
-          :root[tabsintitlebar] #titlebar,
-          :root[tabsintitlebar] #toolbar-menubar,
-          :root[tabsintitlebar] #TabsToolbar {
+          :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+          :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+          :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
             z-index: 1;
           }
-          :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-          :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-          :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+          :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+          :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+          :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
             opacity: 1 !important;
           }
-          :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-          :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-          :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+          :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+          :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+          :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
             opacity: var(--inactive-titlebar-opacity);
           }
+          @supports not -moz-bool-pref("userChrome.tabbar.on_bottom") {
+            :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+              display: flex !important;
+            }
+          }
         }
         /* At Activated Menubar */
         :root:not([chromehidden~="menubar"], [sizemode="fullscreen"])
@@ -6083,21 +6088,26 @@
             :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
               visibility: collapse !important;
             }
-            :root[tabsintitlebar] #titlebar,
-            :root[tabsintitlebar] #toolbar-menubar,
-            :root[tabsintitlebar] #TabsToolbar {
+            :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+            :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+            :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
               z-index: 1;
             }
-            :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-            :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-            :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+            :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+            :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+            :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
               opacity: 1 !important;
             }
-            :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-            :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-            :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+            :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+            :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+            :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
               opacity: var(--inactive-titlebar-opacity);
             }
+            @supports not -moz-bool-pref("userChrome.tabbar.on_bottom") {
+              :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+                display: flex !important;
+              }
+            }
           }
           /* At Activated Menubar */
           :root:not([chromehidden~="menubar"], [sizemode="fullscreen"])
@@ -6245,21 +6255,26 @@
             :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
               visibility: collapse !important;
             }
-            :root[tabsintitlebar] #titlebar,
-            :root[tabsintitlebar] #toolbar-menubar,
-            :root[tabsintitlebar] #TabsToolbar {
+            :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+            :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+            :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
               z-index: 1;
             }
-            :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-            :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-            :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+            :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+            :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+            :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
               opacity: 1 !important;
             }
-            :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-            :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-            :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+            :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+            :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+            :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
               opacity: var(--inactive-titlebar-opacity);
             }
+            @supports not -moz-bool-pref("userChrome.tabbar.on_bottom") {
+              :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+                display: flex !important;
+              }
+            }
           }
           /* At Activated Menubar */
           :root:not([chromehidden~="menubar"], [sizemode="fullscreen"])
@@ -6426,21 +6441,26 @@
               :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
                 visibility: collapse !important;
               }
-              :root[tabsintitlebar] #titlebar,
-              :root[tabsintitlebar] #toolbar-menubar,
-              :root[tabsintitlebar] #TabsToolbar {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
                 z-index: 1;
               }
-              :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-              :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-              :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
                 opacity: 1 !important;
               }
-              :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-              :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-              :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
                 opacity: var(--inactive-titlebar-opacity);
               }
+              @supports not -moz-bool-pref("userChrome.tabbar.on_bottom") {
+                :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+                  display: flex !important;
+                }
+              }
             }
           }
           @media screen and (max-width: 1100px) {
@@ -6596,21 +6616,26 @@
               :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
                 visibility: collapse !important;
               }
-              :root[tabsintitlebar] #titlebar,
-              :root[tabsintitlebar] #toolbar-menubar,
-              :root[tabsintitlebar] #TabsToolbar {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
                 z-index: 1;
               }
-              :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-              :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-              :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
                 opacity: 1 !important;
               }
-              :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-              :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-              :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
                 opacity: var(--inactive-titlebar-opacity);
               }
+              @supports not -moz-bool-pref("userChrome.tabbar.on_bottom") {
+                :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+                  display: flex !important;
+                }
+              }
             }
             /* At Activated Menubar */
             :root:not([chromehidden~="menubar"], [sizemode="fullscreen"])
@@ -6761,21 +6786,26 @@
               :root[inFullscreen]:not([macOSNativeFullscreen]) #menubar-items {
                 visibility: collapse !important;
               }
-              :root[tabsintitlebar] #titlebar,
-              :root[tabsintitlebar] #toolbar-menubar,
-              :root[tabsintitlebar] #TabsToolbar {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar {
                 z-index: 1;
               }
-              :root[tabsintitlebar] #titlebar:-moz-window-inactive,
-              :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive,
-              :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive {
                 opacity: 1 !important;
               }
-              :root[tabsintitlebar] #titlebar:-moz-window-inactive .titlebar-buttonbox,
-              :root[tabsintitlebar] #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
-              :root[tabsintitlebar] #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
+              :root:is([tabsintitlebar], [customtitlebar]) #titlebar:-moz-window-inactive .titlebar-buttonbox,
+              :root:is([tabsintitlebar], [customtitlebar]) #toolbar-menubar:-moz-window-inactive .titlebar-buttonbox,
+              :root:is([tabsintitlebar], [customtitlebar]) #TabsToolbar:-moz-window-inactive .titlebar-buttonbox {
                 opacity: var(--inactive-titlebar-opacity);
               }
+              @supports not -moz-bool-pref("userChrome.tabbar.on_bottom") {
+                :root:is([tabsintitlebar], [customtitlebar]) #nav-bar > .titlebar-buttonbox-container {
+                  display: flex !important;
+                }
+              }
             }
             /* At Activated Menubar */
             :root:not([chromehidden~="menubar"], [sizemode="fullscreen"])
diff --git a/src/tabbar/layout/_window_control.scss b/src/tabbar/layout/_window_control.scss
index 845331b7..f86f6247 100644
--- a/src/tabbar/layout/_window_control.scss
+++ b/src/tabbar/layout/_window_control.scss
@@ -130,7 +130,7 @@ See the above repository for updates as well as full license text. */
     }
   }
 
-  :root[tabsintitlebar] {
+  :root:is([tabsintitlebar], [customtitlebar]) {
     #titlebar,
     #toolbar-menubar,
     #TabsToolbar {
@@ -142,6 +142,12 @@ See the above repository for updates as well as full license text. */
         }
       }
     }
+
+    @include NotOption("userChrome.tabbar.on_bottom") {
+      #nav-bar > .titlebar-buttonbox-container {
+        display: flex !important;
+      }
+    }
   }
 }