--- a/mail/themes/windows/mail/primaryToolbar.css
+++ b/mail/themes/windows/mail/primaryToolbar.css
@@ -246,20 +246,34 @@
     box-shadow: none;
   }
 
   #navigation-toolbox > #toolbar-menubar:not(:-moz-lwtheme) {
     appearance: none;
     border-bottom: 1px solid #aabccf;
   }
 
+  #toolbar-menubar > .titlebar-buttonbox-container {
+    display: none;
+  }
+
   #tabs-toolbar:not(:-moz-lwtheme) {
     position: relative;
   }
 
+  :root[tabsintitlebar] #toolbar-menubar[autohide=true]:not([inactive]) +
+    #tabs-toolbar > .titlebar-buttonbox-container {
+    visibility: visible;
+  }
+
+  :root[tabsintitlebar]:not([chromehidden~="menubar"]) #toolbar-menubar:not([autohide=true]) +
+    #tabs-toolbar > .titlebar-buttonbox-container {
+    display: -moz-box;
+  }
+
   #navigation-toolbox:not(:-moz-lwtheme)::before {
     box-shadow: 0 30px 30px 30px rgba(174, 189, 204, 0.85);
     content: "";
     display: -moz-box;
     margin: 0 60px; /* (30px + 30px) from box-shadow */
     pointer-events: none;
     width: -moz-available;
     z-index: -1;