1 files changed, 18 insertions, 3 deletions
diff --git a/components/layout/fragment_tree/box_fragment.rs b/components/layout/fragment_tree/box_fragment.rs
index 65ad1c4aa93..596556b296c 100644
--- a/components/layout/fragment_tree/box_fragment.rs
+++ b/components/layout/fragment_tree/box_fragment.rs
@@ -16,7 +16,8 @@ use style::logical_geometry::WritingMode;
 use style::properties::ComputedValues;
 use style::values::specified::box_::DisplayOutside;
 
-use super::{BaseFragment, BaseFragmentInfo, CollapsedBlockMargins, Fragment};
+use super::{BaseFragment, BaseFragmentInfo, CollapsedBlockMargins, Fragment, FragmentFlags};
+use crate::ArcRefCell;
 use crate::display_list::ToWebRender;
 use crate::formatting_contexts::Baselines;
 use crate::geom::{
@@ -40,10 +41,14 @@ pub(crate) enum BackgroundMode {
     Normal,
 }
 
+#[derive(Debug, MallocSizeOf)]
+pub(crate) struct BackgroundStyle(#[conditional_malloc_size_of] pub ServoArc<ComputedValues>);
+
+pub(crate) type SharedBackgroundStyle = ArcRefCell<BackgroundStyle>;
+
 #[derive(MallocSizeOf)]
 pub(crate) struct ExtraBackground {
-    #[conditional_malloc_size_of]
-    pub style: ServoArc<ComputedValues>,
+    pub style: SharedBackgroundStyle,
     pub rect: PhysicalRect<Au>,
 }
 
@@ -238,6 +243,16 @@ impl BoxFragment {
         self.margin + self.border + self.padding
     }
 
+    pub(crate) fn is_root_element(&self) -> bool {
+        self.base.flags.intersects(FragmentFlags::IS_ROOT_ELEMENT)
+    }
+
+    pub(crate) fn is_body_element_of_html_element_root(&self) -> bool {
+        self.base
+            .flags
+            .intersects(FragmentFlags::IS_BODY_ELEMENT_OF_HTML_ELEMENT_ROOT)
+    }
+
     pub fn print(&self, tree: &mut PrintTree) {
         tree.new_level(format!(
             "Box\