new file mode 100644
--- /dev/null
+++ b/browser/base/content/browser-window.css
@@ -0,0 +1,16 @@
+/* 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/. */
+
+@import url("chrome://browser/content/browser.css");
+@import url("chrome://browser/content/downloads/downloads.css");
+@import url("chrome://browser/content/places/places.css");
+@import url("chrome://browser/content/usercontext/usercontext.css");
+@import url("chrome://browser/skin/controlcenter/panel.css");
+@import url("chrome://browser/skin/customizableui/panelUI.css");
+@import url("chrome://browser/skin/downloads/downloads.css");
+@import url("chrome://browser/skin/searchbar.css");
+@import url("chrome://browser/skin/places/places.css");
+@import url("chrome://browser/skin/places/editBookmark.css");
+@import url("chrome://browser/skin/");
+@import url("chrome://browser/content/tabbrowser.css");

--- a/browser/base/content/browser.xul
+++ b/browser/base/content/browser.xul
@@ -1,28 +1,17 @@
 #filter substitution
 <?xml version="1.0"?>
 # -*- Mode: HTML -*-
 #
 # 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/.
 
-<?xml-stylesheet href="chrome://browser/content/browser.css" type="text/css"?>
-<?xml-stylesheet href="chrome://browser/content/downloads/downloads.css"?>
-<?xml-stylesheet href="chrome://browser/content/places/places.css" type="text/css"?>
-<?xml-stylesheet href="chrome://browser/content/usercontext/usercontext.css" type="text/css"?>
-<?xml-stylesheet href="chrome://browser/skin/controlcenter/panel.css" type="text/css"?>
-<?xml-stylesheet href="chrome://browser/skin/customizableui/panelUI.css" type="text/css"?>
-<?xml-stylesheet href="chrome://browser/skin/downloads/downloads.css"?>
-<?xml-stylesheet href="chrome://browser/skin/searchbar.css"?>
-<?xml-stylesheet href="chrome://browser/skin/places/places.css"?>
-<?xml-stylesheet href="chrome://browser/skin/places/editBookmark.css"?>
-<?xml-stylesheet href="chrome://browser/skin/" type="text/css"?>
-<?xml-stylesheet href="chrome://browser/content/tabbrowser.css" type="text/css"?>
+<?xml-stylesheet href="chrome://browser/content/browser-window.css" type="text/css"?>
 <?xml-stylesheet href="chrome://browser/skin/compacttheme.css" type="text/css" alternate="yes" title="Light/Dark"?>
 
 # All DTD information is stored in a separate file so that it can be shared by
 # hiddenWindow.xul.
 <!DOCTYPE window [
 #include browser-doctype.inc
 ]>
 

--- a/browser/base/jar.mn
+++ b/browser/base/jar.mn
@@ -50,16 +50,17 @@ browser.jar:
         content/browser/browser-safebrowsing.js       (content/browser-safebrowsing.js)
         content/browser/browser-sidebar.js            (content/browser-sidebar.js)
         content/browser/browser-siteIdentity.js       (content/browser-siteIdentity.js)
         content/browser/browser-sync.js               (content/browser-sync.js)
         content/browser/browser-tabsintitlebar.js       (content/browser-tabsintitlebar.js)
         content/browser/browser-thumbnails.js         (content/browser-thumbnails.js)
         content/browser/browser-trackingprotection.js (content/browser-trackingprotection.js)
         content/browser/browser-webrender.js          (content/browser-webrender.js)
+        content/browser/browser-window.css            (content/browser-window.css)
         content/browser/tab-content.js                (content/tab-content.js)
         content/browser/content.js                    (content/content.js)
         content/browser/defaultthemes/1.header.jpg    (content/defaultthemes/1.header.jpg)
         content/browser/defaultthemes/1.icon.jpg      (content/defaultthemes/1.icon.jpg)
         content/browser/defaultthemes/1.preview.jpg   (content/defaultthemes/1.preview.jpg)
         content/browser/defaultthemes/2.header.jpg    (content/defaultthemes/2.header.jpg)
         content/browser/defaultthemes/2.icon.jpg      (content/defaultthemes/2.icon.jpg)
         content/browser/defaultthemes/2.preview.jpg   (content/defaultthemes/2.preview.jpg)