--- a/dom/html/nsGenericHTMLElement.cpp
+++ b/dom/html/nsGenericHTMLElement.cpp
@@ -1517,16 +1517,22 @@ nsGenericHTMLElement::MapImageBorderAttr
 void
 nsGenericHTMLElement::MapBackgroundInto(const nsMappedAttributes* aAttributes,
                                         GenericSpecifiedValues* aData)
 {
 
   if (!aData->ShouldComputeStyleStruct(NS_STYLE_INHERIT_BIT(Background)))
     return;
 
+  if (aData->IsServo()) {
+    // FIXME(bug 1339711)
+    NS_WARNING("stylo: cannot handle background presentation attribute");
+    return;
+  }
+
   nsPresContext* presContext = aData->PresContext();
 
   if (!aData->PropertyIsSet(eCSSProperty_background_image) &&
       presContext->UseDocumentColors()) {
     // background
     nsAttrValue* value =
       const_cast<nsAttrValue*>(aAttributes->GetAttr(nsGkAtoms::background));
     if (value) {
@@ -1540,19 +1546,16 @@ nsGenericHTMLElement::MapBackgroundInto(
         // put it in the style tree.
         if (value->Type() == nsAttrValue::eURL) {
           value->LoadImage(presContext->Document());
         }
         if (value->Type() == nsAttrValue::eImage) {
           nsCSSValueList* list = backImage->SetListValue();
           list->mValue.SetImageValue(value->GetImageValue());
         }
-      } else {
-        // FIXME(bug 1330041)
-        MOZ_ASSERT_UNREACHABLE("stylo: cannot handle background");
       }
     }
   }
 }
 
 void
 nsGenericHTMLElement::MapBGColorInto(const nsMappedAttributes* aAttributes,
                                      GenericSpecifiedValues* aData)

--- a/dom/mathml/nsMathMLElement.cpp
+++ b/dom/mathml/nsMathMLElement.cpp
@@ -485,16 +485,22 @@ nsMathMLElement::ParseNumericValue(const
   aCSSValue.SetFloatValue(floatValue, cssUnit);
   return true;
 }
 
 void
 nsMathMLElement::MapMathMLAttributesInto(const nsMappedAttributes* aAttributes,
                                          GenericSpecifiedValues* aGenericData)
 {
+  if (aGenericData->IsServo()) {
+    // FIXME (bug 1339711) handle MathML properties in Stylo
+    NS_WARNING("stylo: cannot handle MathML presentation attributes");
+    return;
+  }
+
   nsRuleData* aData = aGenericData->AsGecko();
   if (aData->mSIDs & NS_STYLE_INHERIT_BIT(Font)) {
     // scriptsizemultiplier
     //
     // "Specifies the multiplier to be used to adjust font size due to changes
     // in scriptlevel.
     //
     // values: number

--- a/layout/style/ServoBindingList.h
+++ b/layout/style/ServoBindingList.h
@@ -170,20 +170,56 @@ SERVO_BINDING_FUNC(Servo_DeclarationBloc
                    nsCSSPropertyID property,
                    nsACString* value, bool is_important)
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_RemoveProperty, void,
                    RawServoDeclarationBlockBorrowed declarations,
                    const nsACString* property)
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_RemovePropertyById, void,
                    RawServoDeclarationBlockBorrowed declarations,
                    nsCSSPropertyID property)
-SERVO_BINDING_FUNC(Servo_DeclarationBlock_AddPresValue, void,
+
+// presentation attributes
+SERVO_BINDING_FUNC(Servo_DeclarationBlock_PropertyIsSet, bool,
+                   RawServoDeclarationBlockBorrowed declarations,
+                   nsCSSPropertyID property)
+SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetIdentStringValue, void,
+                   RawServoDeclarationBlockBorrowed declarations,
+                   nsCSSPropertyID property,
+                   const nsAString& value)
+SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetKeywordValue, void,
+                   RawServoDeclarationBlockBorrowed declarations,
+                   nsCSSPropertyID property,
+                   int32_t value)
+SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetIntValue, void,
+                   RawServoDeclarationBlockBorrowed declarations,
+                   nsCSSPropertyID property,
+                   int32_t value)
+SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetPixelValue, void,
                    RawServoDeclarationBlockBorrowed declarations,
                    nsCSSPropertyID property,
-                   nsCSSValueBorrowedMut css_value)
+                   float value)
+SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetPercentValue, void,
+                   RawServoDeclarationBlockBorrowed declarations,
+                   nsCSSPropertyID property,
+                   float value)
+SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetAutoValue, void,
+                   RawServoDeclarationBlockBorrowed declarations,
+                   nsCSSPropertyID property)
+SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetCurrentColor, void,
+                   RawServoDeclarationBlockBorrowed declarations,
+                   nsCSSPropertyID property)
+SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetColorValue, void,
+                   RawServoDeclarationBlockBorrowed declarations,
+                   nsCSSPropertyID property,
+                   nscolor value)
+SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetFontFamily, void,
+                   RawServoDeclarationBlockBorrowed declarations,
+                   const nsAString& value)
+SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetTextDecorationColorOverride, void,
+                   RawServoDeclarationBlockBorrowed declarations)
 
 // CSS supports()
 SERVO_BINDING_FUNC(Servo_CSSSupports2, bool,
                    const nsACString* name, const nsACString* value)
 SERVO_BINDING_FUNC(Servo_CSSSupports, bool,
                    const nsACString* cond)
 
 // Computed style data

--- a/layout/style/ServoSpecifiedValues.cpp
+++ b/layout/style/ServoSpecifiedValues.cpp
@@ -1,13 +1,14 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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/. */
 
+#include "mozilla/ServoBindings.h"
 #include "mozilla/ServoSpecifiedValues.h"
 
 namespace {
 
 #define STYLE_STRUCT(name, checkdata_cb) | NS_STYLE_INHERIT_BIT(name)
 const uint64_t ALL_SIDS = 0
 #include "nsStyleStructList.h"
 ;
@@ -20,8 +21,84 @@ using namespace mozilla;
 ServoSpecifiedValues::ServoSpecifiedValues(nsPresContext* aContext,
                                            RawServoDeclarationBlock* aDecl)
 
   : GenericSpecifiedValues(StyleBackendType::Servo, aContext, ALL_SIDS)
   ,  mDecl(aDecl)
 {
 
 }
+
+bool
+ServoSpecifiedValues::PropertyIsSet(nsCSSPropertyID aId)
+{
+  // We always create fresh ServoSpecifiedValues for each property
+  // mapping, so unlike Gecko there aren't existing properties from
+  // the cascade that we wish to avoid overwriting.
+  //
+  // If a property is being overwritten, that's a bug. Check for it
+  // in debug mode (this is O(n^2) behavior since Servo will traverse
+  // the array each time you add a new property)
+  MOZ_ASSERT(!Servo_DeclarationBlock_PropertyIsSet(mDecl, aId),
+             "Presentation attribute mappers should never attempt to set the same property twice");
+  return false;
+}
+
+void
+ServoSpecifiedValues::SetIdentStringValue(nsCSSPropertyID aId,
+                                          const nsString& aValue)
+{
+  Servo_DeclarationBlock_SetIdentStringValue(mDecl, aId, aValue);
+}
+
+void
+ServoSpecifiedValues::SetKeywordValue(nsCSSPropertyID aId, int32_t aValue)
+{
+  Servo_DeclarationBlock_SetKeywordValue(mDecl, aId, aValue);
+}
+
+void
+ServoSpecifiedValues::SetIntValue(nsCSSPropertyID aId, int32_t aValue)
+{
+  Servo_DeclarationBlock_SetIntValue(mDecl, aId, aValue);
+}
+
+void
+ServoSpecifiedValues::SetPixelValue(nsCSSPropertyID aId, float aValue)
+{
+  Servo_DeclarationBlock_SetPixelValue(mDecl, aId, aValue);
+}
+
+void
+ServoSpecifiedValues::SetPercentValue(nsCSSPropertyID aId, float aValue)
+{
+  Servo_DeclarationBlock_SetPercentValue(mDecl, aId, aValue);
+}
+
+void
+ServoSpecifiedValues::SetAutoValue(nsCSSPropertyID aId)
+{
+  Servo_DeclarationBlock_SetAutoValue(mDecl, aId);
+}
+
+void
+ServoSpecifiedValues::SetCurrentColor(nsCSSPropertyID aId)
+{
+  Servo_DeclarationBlock_SetCurrentColor(mDecl, aId);
+}
+
+void
+ServoSpecifiedValues::SetColorValue(nsCSSPropertyID aId, nscolor aColor)
+{
+  Servo_DeclarationBlock_SetColorValue(mDecl, aId, aColor);
+}
+
+void
+ServoSpecifiedValues::SetFontFamily(const nsString& aValue)
+{
+  Servo_DeclarationBlock_SetFontFamily(mDecl, aValue);
+}
+
+void
+ServoSpecifiedValues::SetTextDecorationColorOverride()
+{
+  Servo_DeclarationBlock_SetTextDecorationColorOverride(mDecl);
+}

--- a/layout/style/ServoSpecifiedValues.h
+++ b/layout/style/ServoSpecifiedValues.h
@@ -19,91 +19,90 @@ namespace mozilla {
 
 class ServoSpecifiedValues final: public GenericSpecifiedValues
 {
 public:
 
   ServoSpecifiedValues(nsPresContext* aContext, RawServoDeclarationBlock* aDecl);
 
   // GenericSpecifiedValues overrides
-  bool PropertyIsSet(nsCSSPropertyID aId) {
-    return false;
-  }
+  bool PropertyIsSet(nsCSSPropertyID aId);
 
   void SetIdentStringValue(nsCSSPropertyID aId,
-                           const nsString& aValue) {
-
-  }
+                           const nsString& aValue);
 
   void SetIdentStringValueIfUnset(nsCSSPropertyID aId,
                                   const nsString& aValue) {
-
+    if (!PropertyIsSet(aId)) {
+      SetIdentStringValue(aId, aValue);
+    }
   }
 
   void SetKeywordValue(nsCSSPropertyID aId,
-                       int32_t aValue) {
-  }
+                       int32_t aValue);
 
   void SetKeywordValueIfUnset(nsCSSPropertyID aId,
                               int32_t aValue) {
-
+    if (!PropertyIsSet(aId)) {
+      SetKeywordValue(aId, aValue);
+    }
   }
 
 
   void SetIntValue(nsCSSPropertyID aId,
-                   int32_t aValue) {
-  }
+                   int32_t aValue);
 
   void SetPixelValue(nsCSSPropertyID aId,
-                     float aValue) {
-  }
+                     float aValue);
 
   void SetPixelValueIfUnset(nsCSSPropertyID aId,
                             float aValue) {
+    if (!PropertyIsSet(aId)) {
+      SetPixelValue(aId, aValue);
+    }
   }
 
   void SetPercentValue(nsCSSPropertyID aId,
-                       float aValue) {
-  }
+                       float aValue);
 
-  void SetAutoValue(nsCSSPropertyID aId) {
-  }
+  void SetAutoValue(nsCSSPropertyID aId);
 
   void SetAutoValueIfUnset(nsCSSPropertyID aId) {
+    if (!PropertyIsSet(aId)) {
+      SetAutoValue(aId);
+    }
   }
 
   void SetPercentValueIfUnset(nsCSSPropertyID aId,
                               float aValue) {
-
+    if (!PropertyIsSet(aId)) {
+      SetPercentValue(aId, aValue);
+    }
   }
 
-  void SetCurrentColor(nsCSSPropertyID aId) {
-
-  }
+  void SetCurrentColor(nsCSSPropertyID aId);
 
   void SetCurrentColorIfUnset(nsCSSPropertyID aId) {
-
+    if (!PropertyIsSet(aId)) {
+      SetCurrentColor(aId);
+    }
   }
 
   void SetColorValue(nsCSSPropertyID aId,
-                     nscolor aValue) {
-
-  }
+                     nscolor aValue);
 
   void SetColorValueIfUnset(nsCSSPropertyID aId,
                             nscolor aValue) {
-
+    if (!PropertyIsSet(aId)) {
+      SetColorValue(aId, aValue);
+    }
   }
 
-  void SetFontFamily(const nsString& aValue) {
-
-  }
-  void SetTextDecorationColorOverride() {
-
-  }
+  void SetFontFamily(const nsString& aValue);
+  void SetTextDecorationColorOverride();
 
 private:
   RefPtr<RawServoDeclarationBlock> mDecl;
 };
 
 } // namespace mozilla
 
 #endif // mozilla_ServoSpecifiedValues_h