diff --git a/dom/base/Element.h b/dom/base/Element.h
index d8f7bc70d..341769878 100644
--- a/dom/base/Element.h
+++ b/dom/base/Element.h
@@ -1617,6 +1617,16 @@ private:
 
   // Data members
   EventStates mState;
+
+public:
+  // Public helper to add or remove event states
+  void SetEventState(mozilla::EventStates aState, bool aAdd) {
+    if (aAdd) {
+      this->AddStates(aState);
+    } else {
+      this->RemoveStates(aState);
+    }
+  }
 };
 
 class RemoveFromBindingManagerRunnable : public mozilla::Runnable
diff --git a/dom/base/nsDOMWindowUtils.cpp b/dom/base/nsDOMWindowUtils.cpp
index 64fbda751..d0e2ffb12 100644
--- a/dom/base/nsDOMWindowUtils.cpp
+++ b/dom/base/nsDOMWindowUtils.cpp
@@ -4095,3 +4095,35 @@ nsTranslationNodeList::GetLength(uint32_t* aRetVal)
   *aRetVal = mLength;
   return NS_OK;
 }
+
+NS_IMETHODIMP
+nsDOMWindowUtils::AddElementEventState(nsIDOMElement* aElement, uint64_t aState)
+{
+  NS_ENSURE_ARG_POINTER(aElement);
+  nsCOMPtr<nsIContent> content = do_QueryInterface(aElement);
+  if (!content) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  mozilla::dom::Element* element = static_cast<mozilla::dom::Element*>(content.get());
+  if (!element) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  element->SetEventState(mozilla::EventStates(aState), true);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDOMWindowUtils::RemoveElementEventState(nsIDOMElement* aElement, uint64_t aState)
+{
+  NS_ENSURE_ARG_POINTER(aElement);
+  nsCOMPtr<nsIContent> content = do_QueryInterface(aElement);
+  if (!content) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  mozilla::dom::Element* element = static_cast<mozilla::dom::Element*>(content.get());
+  if (!element) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  element->SetEventState(mozilla::EventStates(aState), false);
+  return NS_OK;
+}
diff --git a/dom/html/HTMLInputElement.cpp b/dom/html/HTMLInputElement.cpp
index d266dd4db..922ce4462 100644
--- a/dom/html/HTMLInputElement.cpp
+++ b/dom/html/HTMLInputElement.cpp
@@ -2780,10 +2780,16 @@ HTMLInputElement::SetUserInput(const nsAString& aValue)
 void
 HTMLInputElement::SetAutofilled(bool aAutofilled)
 {
+  printf("🔍 AUTOFILL C++: SetAutofilled called with aAutofilled=%s\n", aAutofilled ? "true" : "false");
+  
   if (aAutofilled) {
+    printf("🔍 AUTOFILL C++: Adding NS_EVENT_STATE_AUTOFILL state\n");
     AddStates(NS_EVENT_STATE_AUTOFILL);
+    printf("🔍 AUTOFILL C++: State added successfully\n");
   } else {
+    printf("🔍 AUTOFILL C++: Removing NS_EVENT_STATE_AUTOFILL state\n");
     RemoveStates(NS_EVENT_STATE_AUTOFILL);
+    printf("🔍 AUTOFILL C++: State removed successfully\n");
   }
 }
 
@@ -8462,7 +8468,9 @@ HTMLInputElement::OnValueChanged(bool aNotify, bool aWasInteractiveUserChange)
 
   // Clear autofilled state if this was an interactive user change
   if (aWasInteractiveUserChange && State().HasState(NS_EVENT_STATE_AUTOFILL)) {
+    printf("🔍 AUTOFILL C++: User changed autofilled input, clearing state\n");
     RemoveStates(NS_EVENT_STATE_AUTOFILL);
+    printf("🔍 AUTOFILL C++: Autofill state cleared from input\n");
   }
 
   UpdateAllValidityStates(aNotify);
diff --git a/dom/html/HTMLTextAreaElement.cpp b/dom/html/HTMLTextAreaElement.cpp
index 01c437d09..390f68575 100644
--- a/dom/html/HTMLTextAreaElement.cpp
+++ b/dom/html/HTMLTextAreaElement.cpp
@@ -367,10 +367,16 @@ HTMLTextAreaElement::SetUserInput(const nsAString& aValue)
 void
 HTMLTextAreaElement::SetAutofilled(bool aAutofilled)
 {
+  printf("🔍 AUTOFILL C++: HTMLTextAreaElement::SetAutofilled called with aAutofilled=%s\n", aAutofilled ? "true" : "false");
+  
   if (aAutofilled) {
+    printf("🔍 AUTOFILL C++: Adding NS_EVENT_STATE_AUTOFILL state to textarea\n");
     AddStates(NS_EVENT_STATE_AUTOFILL);
+    printf("🔍 AUTOFILL C++: State added successfully to textarea\n");
   } else {
+    printf("🔍 AUTOFILL C++: Removing NS_EVENT_STATE_AUTOFILL state from textarea\n");
     RemoveStates(NS_EVENT_STATE_AUTOFILL);
+    printf("🔍 AUTOFILL C++: State removed successfully from textarea\n");
   }
 }
 
@@ -1643,7 +1649,9 @@ HTMLTextAreaElement::OnValueChanged(bool aNotify, bool aWasInteractiveUserChange
 
   // Clear autofilled state if this was an interactive user change
   if (aWasInteractiveUserChange && State().HasState(NS_EVENT_STATE_AUTOFILL)) {
+    printf("🔍 AUTOFILL C++: User changed autofilled textarea, clearing state\n");
     RemoveStates(NS_EVENT_STATE_AUTOFILL);
+    printf("🔍 AUTOFILL C++: Autofill state cleared from textarea\n");
   }
 
   // Update the validity state
diff --git a/dom/interfaces/base/nsIDOMWindowUtils.idl b/dom/interfaces/base/nsIDOMWindowUtils.idl
index bbd06c0fe..c783339cd 100644
--- a/dom/interfaces/base/nsIDOMWindowUtils.idl
+++ b/dom/interfaces/base/nsIDOMWindowUtils.idl
@@ -1975,6 +1975,20 @@ interface nsIDOMWindowUtils : nsISupports {
   const long MOUSE_BUTTONS_5TH_BUTTON = 0x10;
   // Buttons are not specified, will be calculated from |aButton|.
   const long MOUSE_BUTTONS_NOT_SPECIFIED = -1;
+
+  /**
+   * Add an EventState bit to an element (privileged only).
+   * @param element The element to modify.
+   * @param state   The EventState bit (see EventStates.h, e.g. NS_EVENT_STATE_AUTOFILL).
+   */
+  void addElementEventState(in nsIDOMElement element, in unsigned long long state);
+
+  /**
+   * Remove an EventState bit from an element (privileged only).
+   * @param element The element to modify.
+   * @param state   The EventState bit.
+   */
+  void removeElementEventState(in nsIDOMElement element, in unsigned long long state);
 };
 
 [scriptable, uuid(c694e359-7227-4392-a138-33c0cc1f15a6)]
diff --git a/layout/style/nsCSSPseudoClassList.h b/layout/style/nsCSSPseudoClassList.h
index fdebca2e6..8ca9c8f28 100644
--- a/layout/style/nsCSSPseudoClassList.h
+++ b/layout/style/nsCSSPseudoClassList.h
@@ -274,6 +274,9 @@ CSS_STATE_PSEUDO_CLASS(mozMeterSubSubOptimum, ":-moz-meter-sub-sub-optimum", 0,
 // Those values should be parsed but do nothing.
 CSS_STATE_PSEUDO_CLASS(mozPlaceholder, ":-moz-placeholder", 0, "", NS_EVENT_STATE_IGNORE)
 
+// Internal-only pseudo-class for autofill highlight
+CSS_STATE_PSEUDO_CLASS(mozAutofillHighlight, ":-moz-autofill-highlight", CSS_PSEUDO_CLASS_ENABLED_IN_UA_SHEETS, "", NS_EVENT_STATE_AUTOFILL)
+
 #ifdef DEFINED_CSS_STATE_PSEUDO_CLASS
 #undef DEFINED_CSS_STATE_PSEUDO_CLASS
 #undef CSS_STATE_PSEUDO_CLASS
diff --git a/layout/style/res/forms.css b/layout/style/res/forms.css
index 0ae49d7e8..9f77e7fd6 100644
--- a/layout/style/res/forms.css
+++ b/layout/style/res/forms.css
@@ -1157,3 +1157,9 @@ input[type="date"],
 input[type="time"] {
   overflow: hidden !important;
 }
+
+/* Autofill highlight for internal-only pseudo-class */
+input:-moz-autofill-highlight,
+textarea:-moz-autofill-highlight {
+  background-color: #ffff99 !important;
+}
diff --git a/toolkit/components/formautofill/FormAutofillContentService.js b/toolkit/components/formautofill/FormAutofillContentService.js
index df95cde67..4756663c1 100644
--- a/toolkit/components/formautofill/FormAutofillContentService.js
+++ b/toolkit/components/formautofill/FormAutofillContentService.js
@@ -11,6 +11,8 @@
 
 "use strict";
 
+console.log('🔍 AUTOFILL: FormAutofillContentService.js loaded');
+
 const { classes: Cc, interfaces: Ci, utils: Cu, results: Cr } = Components;
 
 Cu.import("resource://gre/modules/Services.jsm");
@@ -29,6 +31,19 @@ function FormHandler(aForm, aWindow) {
   this.window = aWindow;
 
   this.fieldDetails = [];
+
+  // Add a reset event listener to clear autofill state
+  this.form.addEventListener("reset", () => {
+    console.log('Form reset detected, clearing autofill state');
+    for (let element of this.form.elements) {
+      if (typeof element.setAutofilled === "function") {
+        element.setAutofilled(false);
+        console.log('setAutofilled(false) called on', element);
+      }
+    }
+    // Optionally, clear fieldDetails if you want to force re-collection
+    // this.fieldDetails = [];
+  });
 }
 
 FormHandler.prototype = {
@@ -130,7 +145,9 @@ FormHandler.prototype = {
       return "cancel";
     }
 
+    console.log('🔍 AUTOFILL: About to call autofillFormFields with result:', result);
     this.autofillFormFields(result);
+    console.log('🔍 AUTOFILL: autofillFormFields completed');
 
     return "success";
   }),
@@ -226,22 +243,38 @@ FormHandler.prototype = {
    *        }
    */
   autofillFormFields(aAutofillResult) {
+    console.log('🔍 AUTOFILL: autofillFormFields called with', aAutofillResult);
+    
     for (let field of aAutofillResult.fields) {
+      console.log('🔍 AUTOFILL: Processing field', field);
+      
       // Get the field details, if it was processed by the user interface.
       let fieldDetail = this.fieldDetails
                             .find(f => f.section == field.section &&
                                        f.addressType == field.addressType &&
                                        f.contactType == field.contactType &&
                                        f.fieldName == field.fieldName);
+      
+      console.log('🔍 AUTOFILL: Found fieldDetail?', !!fieldDetail, fieldDetail);
+      
       if (!fieldDetail) {
+        console.log('🔍 AUTOFILL: No fieldDetail found, skipping');
         continue;
       }
 
+      console.log('🔍 AUTOFILL: Setting value on element', fieldDetail.element);
       fieldDetail.element.value = field.value;
       
       // Set the autofilled state on the element
+      console.log('🔍 AUTOFILL: Checking if setAutofilled exists on element');
+      console.log('🔍 AUTOFILL: setAutofilled type:', typeof fieldDetail.element.setAutofilled);
+      
       if (typeof fieldDetail.element.setAutofilled === 'function') {
+        console.log('🔍 AUTOFILL: Calling setAutofilled(true) on element');
         fieldDetail.element.setAutofilled(true);
+        console.log('🔍 AUTOFILL: setAutofilled(true) called successfully');
+      } else {
+        console.log('🔍 AUTOFILL: setAutofilled is not a function on this element');
       }
     }
   },