--- a/devtools/shared/css/generated/properties-db.js
+++ b/devtools/shared/css/generated/properties-db.js
@@ -3255,16 +3255,18 @@ exports.CSS_PROPERTIES = {
       "-moz-mac-disclosure-button-closed",
       "-moz-mac-disclosure-button-open",
       "-moz-mac-fullscreen-button",
       "-moz-mac-help-button",
       "-moz-mac-source-list",
       "-moz-mac-source-list-selection",
       "-moz-mac-vibrancy-dark",
       "-moz-mac-vibrancy-light",
+      "-moz-mac-vibrant-titlebar-dark",
+      "-moz-mac-vibrant-titlebar-light",
       "-moz-max-content",
       "-moz-middle-with-baseline",
       "-moz-min-content",
       "-moz-none",
       "-moz-popup",
       "-moz-pre-space",
       "-moz-pull-down-menu",
       "-moz-radial-gradient",

--- a/layout/style/nsCSSProps.cpp
+++ b/layout/style/nsCSSProps.cpp
@@ -1129,16 +1129,18 @@ const KTableEntry nsCSSProps::kColorKTab
   { eCSSKeyword__moz_mac_menuselect, LookAndFeel::eColorID__moz_mac_menuselect },
   { eCSSKeyword__moz_mac_menushadow, LookAndFeel::eColorID__moz_mac_menushadow },
   { eCSSKeyword__moz_mac_menutextdisable, LookAndFeel::eColorID__moz_mac_menutextdisable },
   { eCSSKeyword__moz_mac_menutextselect, LookAndFeel::eColorID__moz_mac_menutextselect },
   { eCSSKeyword__moz_mac_disabledtoolbartext, LookAndFeel::eColorID__moz_mac_disabledtoolbartext },
   { eCSSKeyword__moz_mac_secondaryhighlight, LookAndFeel::eColorID__moz_mac_secondaryhighlight },
   { eCSSKeyword__moz_mac_vibrancy_light, LookAndFeel::eColorID__moz_mac_vibrancy_light },
   { eCSSKeyword__moz_mac_vibrancy_dark, LookAndFeel::eColorID__moz_mac_vibrancy_dark },
+  { eCSSKeyword__moz_mac_vibrant_titlebar_light, LookAndFeel::eColorID__moz_mac_vibrant_titlebar_light },
+  { eCSSKeyword__moz_mac_vibrant_titlebar_dark,  LookAndFeel::eColorID__moz_mac_vibrant_titlebar_dark },
   { eCSSKeyword__moz_mac_menuitem, LookAndFeel::eColorID__moz_mac_menuitem },
   { eCSSKeyword__moz_mac_active_menuitem, LookAndFeel::eColorID__moz_mac_active_menuitem },
   { eCSSKeyword__moz_mac_menupopup, LookAndFeel::eColorID__moz_mac_menupopup },
   { eCSSKeyword__moz_mac_source_list, LookAndFeel::eColorID__moz_mac_source_list },
   { eCSSKeyword__moz_mac_source_list_selection, LookAndFeel::eColorID__moz_mac_source_list_selection },
   { eCSSKeyword__moz_mac_active_source_list_selection, LookAndFeel::eColorID__moz_mac_active_source_list_selection },
   { eCSSKeyword__moz_mac_tooltip, LookAndFeel::eColorID__moz_mac_tooltip },
   { eCSSKeyword__moz_menuhover, LookAndFeel::eColorID__moz_menuhover },

--- a/widget/LookAndFeel.h
+++ b/widget/LookAndFeel.h
@@ -155,16 +155,18 @@ public:
     eColorID__moz_mac_disabledtoolbartext,
     //inactive light hightlight
     eColorID__moz_mac_secondaryhighlight,
 
     // Font smoothing background colors needed by the Mac OS X theme, based
     // on -moz-appearance names
     eColorID__moz_mac_vibrancy_light,
     eColorID__moz_mac_vibrancy_dark,
+    eColorID__moz_mac_vibrant_titlebar_light,
+    eColorID__moz_mac_vibrant_titlebar_dark,
     eColorID__moz_mac_menupopup,
     eColorID__moz_mac_menuitem,
     eColorID__moz_mac_active_menuitem,
     eColorID__moz_mac_source_list,
     eColorID__moz_mac_source_list_selection,
     eColorID__moz_mac_active_source_list_selection,
     eColorID__moz_mac_tooltip,
 

--- a/widget/cocoa/nsLookAndFeel.mm
+++ b/widget/cocoa/nsLookAndFeel.mm
@@ -331,21 +331,23 @@ nsLookAndFeel::NativeGetColor(ColorID aI
     // colors, in the chrome-only -moz-font-smoothing-background-color property.
     // This property is used for text on "vibrant" -moz-appearances.
     // The colors have been obtained from the system on 10.12.6 using the
     // program at https://bugzilla.mozilla.org/attachment.cgi?id=8907533 .
     // We could obtain them at runtime, but doing so may be expensive and
     // requires the use of the private API
     // -[NSVisualEffectView fontSmoothingBackgroundColor].
     case eColorID__moz_mac_vibrancy_light:
+    case eColorID__moz_mac_vibrant_titlebar_light:
     case eColorID__moz_mac_source_list:
     case eColorID__moz_mac_tooltip:
       aColor = NS_RGB(0xf7,0xf7,0xf7);
       break;
     case eColorID__moz_mac_vibrancy_dark:
+    case eColorID__moz_mac_vibrant_titlebar_dark:
       aColor = NS_RGB(0x28,0x28,0x28);
       break;
     case eColorID__moz_mac_menupopup:
     case eColorID__moz_mac_menuitem:
       aColor = NS_RGB(0xe6,0xe6,0xe6);
       break;
     case eColorID__moz_mac_source_list_selection:
       aColor = NS_RGB(0xc8,0xc8,0xc8);

--- a/widget/nsXPLookAndFeel.cpp
+++ b/widget/nsXPLookAndFeel.cpp
@@ -243,16 +243,18 @@ const char nsXPLookAndFeel::sColorPrefs[
   "ui.-moz-mac-menuselect",
   "ui.-moz-mac-menushadow",
   "ui.-moz-mac-menutextdisable",
   "ui.-moz-mac-menutextselect",
   "ui.-moz_mac_disabledtoolbartext",
   "ui.-moz-mac-secondaryhighlight",
   "ui.-moz-mac-vibrancy-light",
   "ui.-moz-mac-vibrancy-dark",
+  "ui.-moz-mac-vibrant-titlebar-light",
+  "ui.-moz-mac-vibrant-titlebar-dark",
   "ui.-moz-mac-menupopup",
   "ui.-moz-mac-menuitem",
   "ui.-moz-mac-active-menuitem",
   "ui.-moz-mac-source-list",
   "ui.-moz-mac-source-list-selection",
   "ui.-moz-mac-active-source-list-selection",
   "ui.-moz-mac-tooltip",
   "ui.-moz-win-mediatext",
@@ -672,18 +674,20 @@ nsXPLookAndFeel::GetStandinForNativeColo
       result = NS_RGB(0x88, 0x88, 0x88); break;
     case eColorID__moz_mac_menutextselect:
       result = NS_RGB(0xFF, 0xFF, 0xFF); break;
     case eColorID__moz_mac_disabledtoolbartext:
       result = NS_RGB(0x3F, 0x3F, 0x3F); break;
     case eColorID__moz_mac_secondaryhighlight:
       result = NS_RGB(0xD4, 0xD4, 0xD4); break;
     case eColorID__moz_mac_vibrancy_light:
+    case eColorID__moz_mac_vibrant_titlebar_light:
       result = NS_RGB(0xf7, 0xf7, 0xf7); break;
     case eColorID__moz_mac_vibrancy_dark:
+    case eColorID__moz_mac_vibrant_titlebar_dark:
       result = NS_RGB(0x28, 0x28, 0x28); break;
     case eColorID__moz_mac_menupopup:
       result = NS_RGB(0xe6, 0xe6, 0xe6); break;
     case eColorID__moz_mac_menuitem:
       result = NS_RGB(0xe6, 0xe6, 0xe6); break;
     case eColorID__moz_mac_active_menuitem:
       result = NS_RGB(0x0a, 0x64, 0xdc); break;
     case eColorID__moz_mac_source_list: