diff --git a/chrome/menubar_in_main_toolbar.css b/chrome/menubar_in_main_toolbar.css
new file mode 100644
index 0000000..fcd3d0d
--- /dev/null
+++ b/chrome/menubar_in_main_toolbar.css
@@ -0,0 +1,26 @@
+/* Source file https://github.com/MrOtherGuy/firefox-csshacks/tree/master/chrome/menubar_in_main_toolbar.css made available under Mozilla Public License v. 2.0
+See the above repository for updates as well as full license text. */
+
+/* Make menubar permanently enabled or this isn't going to work */
+
+#navigator-toolbox{ --uc-menubar-height: 36px }
+:root[uidensity="compact"] #navigator-toolbox{ --uc-menubar-height: 30px }
+
+#titlebar{ -moz-box-direction: reverse; -moz-appearance: none !important; }
+@media (-moz-os-version: windows-win10){
+  :root[sizemode="maximized"][tabsintitlebar] #TabsToolbar{ margin-top: 8px !important; }
+}
+#toolbar-menubar{
+  margin-bottom: calc(0px - var(--uc-menubar-height));
+  height: var(--uc-menubar-height);
+  position: relative;
+  z-index: 2;
+}
+
+#menubar-items{ -moz-box-pack: center }
+/* Adjust to fit menubar items - 300px works for English locale */
+#nav-bar{ padding-left: 300px; }
+
+#toolbar-menubar > .titlebar-buttonbox-container{ display: none }
+:root[tabsintitlebar][sizemode="normal"] .titlebar-spacer,
+:root[tabsintitlebar] #TabsToolbar > .titlebar-buttonbox-container{ display: -moz-box !important; }
diff --git a/html_resources/tagmap.json b/html_resources/tagmap.json
index 4ce57c4..a1e3c78 100644
--- a/html_resources/tagmap.json
+++ b/html_resources/tagmap.json
@@ -93,5 +93,6 @@
 "vertical_context_navigation.css":["navigation","menu","popup"],
 "vertical_context_navigation_v2.css":["navigation","menu","popup"],
 "vertical_menubar.css":["menubar","hack"],
-"window_control_placeholder_support.css":["window-control","patch"]
+"window_control_placeholder_support.css":["window-control","patch"],
+"menubar_in_main_toolbar.css":["menubar","nav-bar","minimal","toolbars"]
 }
diff --git a/tags.csv b/tags.csv
index 1d96e2f..2abe73a 100644
--- a/tags.csv
+++ b/tags.csv
@@ -93,3 +93,4 @@ vertical_context_navigation.css,navigation,menu,popup
 vertical_context_navigation_v2.css,navigation,menu,popup
 vertical_menubar.css,menubar,hack
 window_control_placeholder_support.css,window-control,patch
+menubar_in_main_toolbar.css,menubar,nav-bar,minimal,toolbars