diff --git a/content/html/document/src/nsHTMLDocument.cpp b/content/html/document/src/nsHTMLDocument.cpp
index a050eef008d9..d1ec6ecdbc81 100644
--- a/content/html/document/src/nsHTMLDocument.cpp
+++ b/content/html/document/src/nsHTMLDocument.cpp
@@ -137,7 +137,7 @@ nsHTMLDocument::nsHTMLDocument()
   mNamedItems = nsnull;
   mParser = nsnull;
   nsHTMLAtoms::AddrefAtoms();
-  mDTDMode = eDTDMode_NoQuirks;
+  mDTDMode = eDTDMode_Nav;
   mCSSLoader = nsnull;
 
   // Find/Search Init
@@ -299,6 +299,25 @@ nsHTMLDocument::GetContentType(nsString& aContentType) const
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsHTMLDocument::CreateShell(nsIPresContext* aContext,
+                            nsIViewManager* aViewManager,
+                            nsIStyleSet* aStyleSet,
+                            nsIPresShell** aInstancePtrResult)
+{
+  nsresult result = nsMarkupDocument::CreateShell(aContext,
+                                                  aViewManager,
+                                                  aStyleSet,
+                                                  aInstancePtrResult);
+
+  if (NS_SUCCEEDED(result)) {
+    aContext->SetCompatibilityMode(((eDTDMode_NoQuirks == mDTDMode) ? 
+                                    eCompatibility_Standard : 
+                                    eCompatibility_NavQuirks));
+  }
+  return result;
+}
+
 NS_IMETHODIMP
 nsHTMLDocument::StartDocumentLoad(nsIURI *aURL,
                                   nsIContentViewerContainer* aContainer,
@@ -631,6 +650,10 @@ nsHTMLDocument::GetCSSLoader(nsICSSLoader*& aLoader)
   if (! mCSSLoader) {
     result = NS_NewCSSLoader(this, &mCSSLoader);
   }
+  if (mCSSLoader) {
+    mCSSLoader->SetCaseSensitive(PR_FALSE);
+    mCSSLoader->SetQuirkMode(PRBool(eDTDMode_NoQuirks != mDTDMode));
+  }
   aLoader = mCSSLoader;
   NS_IF_ADDREF(aLoader);
   return result;
@@ -648,6 +671,9 @@ NS_IMETHODIMP
 nsHTMLDocument::SetDTDMode(nsDTDMode aMode)
 {
   mDTDMode = aMode;
+  if (mCSSLoader) {
+    mCSSLoader->SetQuirkMode(PRBool(eDTDMode_NoQuirks != mDTDMode));
+  }
   return NS_OK;
 }
 
diff --git a/content/html/document/src/nsHTMLDocument.h b/content/html/document/src/nsHTMLDocument.h
index d71964725cb0..a3aaa4eff2b9 100644
--- a/content/html/document/src/nsHTMLDocument.h
+++ b/content/html/document/src/nsHTMLDocument.h
@@ -54,6 +54,11 @@ public:
 
   NS_IMETHOD GetContentType(nsString& aContentType) const;
 
+  NS_IMETHOD CreateShell(nsIPresContext* aContext,
+                         nsIViewManager* aViewManager,
+                         nsIStyleSet* aStyleSet,
+                         nsIPresShell** aInstancePtrResult);
+
   NS_IMETHOD StartDocumentLoad(nsIURI* aUrl, 
                                nsIContentViewerContainer* aContainer,
                                nsIStreamListener** aDocListener,
diff --git a/layout/html/document/src/nsHTMLDocument.cpp b/layout/html/document/src/nsHTMLDocument.cpp
index a050eef008d9..d1ec6ecdbc81 100644
--- a/layout/html/document/src/nsHTMLDocument.cpp
+++ b/layout/html/document/src/nsHTMLDocument.cpp
@@ -137,7 +137,7 @@ nsHTMLDocument::nsHTMLDocument()
   mNamedItems = nsnull;
   mParser = nsnull;
   nsHTMLAtoms::AddrefAtoms();
-  mDTDMode = eDTDMode_NoQuirks;
+  mDTDMode = eDTDMode_Nav;
   mCSSLoader = nsnull;
 
   // Find/Search Init
@@ -299,6 +299,25 @@ nsHTMLDocument::GetContentType(nsString& aContentType) const
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsHTMLDocument::CreateShell(nsIPresContext* aContext,
+                            nsIViewManager* aViewManager,
+                            nsIStyleSet* aStyleSet,
+                            nsIPresShell** aInstancePtrResult)
+{
+  nsresult result = nsMarkupDocument::CreateShell(aContext,
+                                                  aViewManager,
+                                                  aStyleSet,
+                                                  aInstancePtrResult);
+
+  if (NS_SUCCEEDED(result)) {
+    aContext->SetCompatibilityMode(((eDTDMode_NoQuirks == mDTDMode) ? 
+                                    eCompatibility_Standard : 
+                                    eCompatibility_NavQuirks));
+  }
+  return result;
+}
+
 NS_IMETHODIMP
 nsHTMLDocument::StartDocumentLoad(nsIURI *aURL,
                                   nsIContentViewerContainer* aContainer,
@@ -631,6 +650,10 @@ nsHTMLDocument::GetCSSLoader(nsICSSLoader*& aLoader)
   if (! mCSSLoader) {
     result = NS_NewCSSLoader(this, &mCSSLoader);
   }
+  if (mCSSLoader) {
+    mCSSLoader->SetCaseSensitive(PR_FALSE);
+    mCSSLoader->SetQuirkMode(PRBool(eDTDMode_NoQuirks != mDTDMode));
+  }
   aLoader = mCSSLoader;
   NS_IF_ADDREF(aLoader);
   return result;
@@ -648,6 +671,9 @@ NS_IMETHODIMP
 nsHTMLDocument::SetDTDMode(nsDTDMode aMode)
 {
   mDTDMode = aMode;
+  if (mCSSLoader) {
+    mCSSLoader->SetQuirkMode(PRBool(eDTDMode_NoQuirks != mDTDMode));
+  }
   return NS_OK;
 }
 
diff --git a/layout/html/document/src/nsHTMLDocument.h b/layout/html/document/src/nsHTMLDocument.h
index d71964725cb0..a3aaa4eff2b9 100644
--- a/layout/html/document/src/nsHTMLDocument.h
+++ b/layout/html/document/src/nsHTMLDocument.h
@@ -54,6 +54,11 @@ public:
 
   NS_IMETHOD GetContentType(nsString& aContentType) const;
 
+  NS_IMETHOD CreateShell(nsIPresContext* aContext,
+                         nsIViewManager* aViewManager,
+                         nsIStyleSet* aStyleSet,
+                         nsIPresShell** aInstancePtrResult);
+
   NS_IMETHOD StartDocumentLoad(nsIURI* aUrl, 
                                nsIContentViewerContainer* aContainer,
                                nsIStreamListener** aDocListener,