--- a/layout/base/nsDocumentViewer.cpp
+++ b/layout/base/nsDocumentViewer.cpp
@@ -2433,16 +2433,22 @@ nsDocumentViewer::CreateStyleSet(nsIDocu
     }
 
     sheet = cache->FormsSheet();
     if (sheet) {
       styleSet->PrependStyleSheet(SheetType::Agent, sheet);
     }
 
     if (aDocument->LoadsFullXULStyleSheetUpFront()) {
+      // This is the only place components.css gets loaded, unlike xul.css
+      sheet = cache->XULComponentsSheet();
+      if (sheet) {
+        styleSet->PrependStyleSheet(SheetType::Agent, sheet);
+      }
+
       // nsXULElement::BindToTree loads xul.css on-demand if we don't load it
       // up-front here.
       sheet = cache->XULSheet();
       if (sheet) {
         styleSet->PrependStyleSheet(SheetType::Agent, sheet);
       }
     }
 

--- a/layout/style/nsLayoutStylesheetCache.cpp
+++ b/layout/style/nsLayoutStylesheetCache.cpp
@@ -152,16 +152,27 @@ nsLayoutStylesheetCache::XULSheet()
     LoadSheetURL("chrome://global/content/xul.css",
                  &mXULSheet, eAgentSheetFeatures, eCrash);
   }
 
   return mXULSheet;
 }
 
 StyleSheet*
+nsLayoutStylesheetCache::XULComponentsSheet()
+{
+  if (!mXULComponentsSheet) {
+    LoadSheetURL("chrome://global/content/components.css",
+                 &mXULComponentsSheet, eAgentSheetFeatures, eCrash);
+  }
+
+  return mXULComponentsSheet;
+}
+
+StyleSheet*
 nsLayoutStylesheetCache::QuirkSheet()
 {
   return mQuirkSheet;
 }
 
 StyleSheet*
 nsLayoutStylesheetCache::SVGSheet()
 {
@@ -308,16 +319,17 @@ nsLayoutStylesheetCache::SizeOfIncluding
   MEASURE(mNumberControlSheet);
   MEASURE(mQuirkSheet);
   MEASURE(mSVGSheet);
   MEASURE(mScrollbarsSheet);
   MEASURE(mUASheet);
   MEASURE(mUserChromeSheet);
   MEASURE(mUserContentSheet);
   MEASURE(mXULSheet);
+  MEASURE(mXULComponentsSheet);
 
   // Measurement of the following members may be added later if DMD finds it is
   // worthwhile:
   // - gCSSLoader_Gecko
   // - gCSSLoader_Servo
 
   return n;
 }
@@ -348,16 +360,17 @@ nsLayoutStylesheetCache::nsLayoutStylesh
                &mMinimalXULSheet, eAgentSheetFeatures, eCrash);
   LoadSheetURL("resource://gre-resources/quirk.css",
                &mQuirkSheet, eAgentSheetFeatures, eCrash);
   LoadSheetURL("resource://gre/res/svg.css",
                &mSVGSheet, eAgentSheetFeatures, eCrash);
   if (XRE_IsParentProcess()) {
     // We know we need xul.css for the UI, so load that now too:
     XULSheet();
+    XULComponentsSheet();
   }
 
   auto& userContentSheetURL = aType == StyleBackendType::Gecko ?
                               gUserContentSheetURL_Gecko :
                               gUserContentSheetURL_Servo;
   if (userContentSheetURL) {
     MOZ_ASSERT(XRE_IsContentProcess(), "Only used in content processes.");
     LoadSheet(userContentSheetURL, &mUserContentSheet, eUserSheetFeatures, eLogToConsole);

--- a/layout/style/nsLayoutStylesheetCache.h
+++ b/layout/style/nsLayoutStylesheetCache.h
@@ -58,16 +58,17 @@ class nsLayoutStylesheetCache final
   // pref is disabled.
   mozilla::StyleSheet* NumberControlSheet();
   mozilla::StyleSheet* UserContentSheet();
   mozilla::StyleSheet* UserChromeSheet();
   mozilla::StyleSheet* UASheet();
   mozilla::StyleSheet* HTMLSheet();
   mozilla::StyleSheet* MinimalXULSheet();
   mozilla::StyleSheet* XULSheet();
+  mozilla::StyleSheet* XULComponentsSheet();
   mozilla::StyleSheet* QuirkSheet();
   mozilla::StyleSheet* SVGSheet();
   mozilla::StyleSheet* MathMLSheet();
   mozilla::StyleSheet* CounterStylesSheet();
   mozilla::StyleSheet* NoScriptSheet();
   mozilla::StyleSheet* NoFramesSheet();
   mozilla::StyleSheet* ChromePreferenceSheet(nsPresContext* aPresContext);
   mozilla::StyleSheet* ContentPreferenceSheet(nsPresContext* aPresContext);
@@ -126,11 +127,12 @@ private:
   RefPtr<mozilla::StyleSheet> mNumberControlSheet;
   RefPtr<mozilla::StyleSheet> mQuirkSheet;
   RefPtr<mozilla::StyleSheet> mSVGSheet;
   RefPtr<mozilla::StyleSheet> mScrollbarsSheet;
   RefPtr<mozilla::StyleSheet> mUASheet;
   RefPtr<mozilla::StyleSheet> mUserChromeSheet;
   RefPtr<mozilla::StyleSheet> mUserContentSheet;
   RefPtr<mozilla::StyleSheet> mXULSheet;
+  RefPtr<mozilla::StyleSheet> mXULComponentsSheet;
 };
 
 #endif

new file mode 100644
--- /dev/null
+++ b/toolkit/content/components.css
@@ -0,0 +1,9 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* ===== components.css =================================================
+  == Styles ported from XBL <resources>, loaded as UA styles in every XUL doc
+  ======================================================================= */
+
+@import url("chrome://global/skin/menu.css");

--- a/toolkit/content/jar.mn
+++ b/toolkit/content/jar.mn
@@ -1,14 +1,15 @@
 toolkit.jar:
 %  content global %content/global/ contentaccessible=yes
 *  content/global/license.html
    content/global/XPCNativeWrapper.js
    content/global/minimal-xul.css
 *  content/global/xul.css
+   content/global/components.css
    content/global/textbox.css
    content/global/menulist.css
    content/global/autocomplete.css
    content/global/aboutAbout.js
    content/global/aboutAbout.xhtml
 #ifdef MOZILLA_OFFICIAL
    content/global/aboutRights.xhtml
 #else

--- a/toolkit/themes/linux/global/global.css
+++ b/toolkit/themes/linux/global/global.css
@@ -3,17 +3,16 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 /* ===== global.css =====================================================
   == Styles that apply everywhere.
   ======================================================================= */
 
 /* all localizable skin settings shall live here */
 @import url("chrome://global/locale/intl.css");
-@import url("chrome://global/skin/menu.css");
 
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
 
 /* ::::: XBL bindings ::::: */
 
 menulist > menupopup {
   -moz-binding: url("chrome://global/content/bindings/popup.xml#popup-scrollbars");
 }

--- a/toolkit/themes/osx/global/global.css
+++ b/toolkit/themes/osx/global/global.css
@@ -1,15 +1,14 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 /* all localizable skin settings shall live here */
 @import url("chrome://global/locale/intl.css");
-@import url("chrome://global/skin/menu.css");
 
 %include shared.inc
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
 
 /* ::::: XBL bindings ::::: */
 
 menulist > menupopup {
   -moz-binding: url("chrome://global/content/bindings/popup.xml#popup-scrollbars");

--- a/toolkit/themes/windows/global/global.css
+++ b/toolkit/themes/windows/global/global.css
@@ -3,17 +3,16 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 /* ===== global.css =====================================================
   == Styles that apply everywhere.
   ======================================================================= */
 
 /* all localizable skin settings shall live here */
 @import url("chrome://global/locale/intl.css");
-@import url("chrome://global/skin/menu.css");
 
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
 
 /* ::::: XBL bindings ::::: */
 
 menulist > menupopup {
   -moz-binding: url("chrome://global/content/bindings/popup.xml#popup-scrollbars");
 }