diff --git a/layout/xul/nsScrollbarFrame.cpp b/layout/xul/nsScrollbarFrame.cpp
index 4b8d5331e6a4..74ce3b5c6544 100644
--- a/layout/xul/nsScrollbarFrame.cpp
+++ b/layout/xul/nsScrollbarFrame.cpp
@@ -284,19 +284,6 @@ int32_t nsScrollbarFrame::MoveToNewPosition() {
 
 nsresult nsScrollbarFrame::CreateAnonymousContent(
     nsTArray<ContentInfo>& aElements) {
-  // clang-format off
-
-  // <xul:scrollbarbutton sbattr="scrollbar-up-top" type="decrement" xbl:inherits="curpos,maxpos,disabled"/>
-  // <xul:scrollbarbutton sbattr="scrollbar-down-top" type="increment" xbl:inherits="curpos,maxpos,disabled"/>
-  // <xul:slider flex="1" xbl:inherits="disabled,curpos,maxpos,pageincrement,increment,orient">
-  //   <xul:thumb sbattr="scrollbar-thumb" xbl:inherits="orient,collapsed=disabled"
-  //              align="center" pack="center"/>
-  // </xul:slider>
-  // <xul:scrollbarbutton sbattr="scrollbar-up-bottom" type="decrement" xbl:inherits="curpos,maxpos,disabled"/>
-  // <xul:scrollbarbutton sbattr="scrollbar-down-bottom" type="increment" xbl:inherits="curpos,maxpos,disabled"/>
-
-  // clang-format on
-
   nsNodeInfoManager* nodeInfoManager = mContent->NodeInfo()->NodeInfoManager();
 
   Element* el(GetContent()->AsElement());
@@ -352,8 +339,6 @@ nsresult nsScrollbarFrame::CreateAnonymousContent(
       getter_AddRefs(mThumb),
       nodeInfoManager->GetNodeInfo(nsGkAtoms::thumb, nullptr, kNameSpaceID_XUL,
                                    nsINode::ELEMENT_NODE));
-  mThumb->SetAttr(kNameSpaceID_None, nsGkAtoms::sbattr,
-                  NS_LITERAL_STRING("scrollbar-thumb"), false);
   mThumb->SetAttr(kNameSpaceID_None, nsGkAtoms::orient, orient, false);
   mThumb->SetAttr(kNameSpaceID_None, nsGkAtoms::align,
                   NS_LITERAL_STRING("center"), false);
diff --git a/toolkit/content/minimal-xul.css b/toolkit/content/minimal-xul.css
index 9e1d3d9f29d2..d0e5a2681333 100644
--- a/toolkit/content/minimal-xul.css
+++ b/toolkit/content/minimal-xul.css
@@ -152,7 +152,7 @@ scrollbar[value="hidden"] {
 }
 
 @media (-moz-scrollbar-thumb-proportional) {
-  thumb[sbattr="scrollbar-thumb"] {
+  thumb {
     -moz-box-flex: 1;
   }
 }