diff --git a/Userland/Libraries/LibWeb/Layout/LayoutState.cpp b/Userland/Libraries/LibWeb/Layout/LayoutState.cpp
index 0df4a9f558..015e1b2d73 100644
--- a/Userland/Libraries/LibWeb/Layout/LayoutState.cpp
+++ b/Userland/Libraries/LibWeb/Layout/LayoutState.cpp
@@ -82,8 +82,8 @@ static CSSPixelRect measure_scrollable_overflow(Box const& box)
     auto scrollable_overflow_rect = paintable_box.absolute_padding_box_rect();
 
     // - All line boxes directly contained by the scroll container.
-    if (box.is_block_container() && box.children_are_inline()) {
-        auto const& line_boxes = verify_cast<Painting::PaintableWithLines>(*box.paintable_box()).line_boxes();
+    if (is<Painting::PaintableWithLines>(box.paintable())) {
+        auto const& line_boxes = static_cast<Painting::PaintableWithLines const&>(*box.paintable()).line_boxes();
         for (auto const& line_box : line_boxes) {
             scrollable_overflow_rect = scrollable_overflow_rect.united(line_box.absolute_rect());
         }
@@ -238,8 +238,7 @@ void LayoutState::commit(Box& root)
         node.set_paintable(paintable);
 
         // For boxes, transfer all the state needed for painting.
-        if (is<Layout::Box>(node)) {
-            auto& box = static_cast<Layout::Box const&>(node);
+        if (paintable && is<Painting::PaintableBox>(*paintable)) {
             auto& paintable_box = static_cast<Painting::PaintableBox&>(*paintable);
             paintable_box.set_offset(used_values.offset);
             paintable_box.set_content_size(used_values.content_width(), used_values.content_height());
@@ -250,7 +249,7 @@ void LayoutState::commit(Box& root)
                 paintable_box.set_table_cell_coordinates(used_values.table_cell_coordinates().value());
             }
 
-            if (is<Layout::BlockContainer>(box)) {
+            if (is<Painting::PaintableWithLines>(paintable_box)) {
                 auto& paintable_with_lines = static_cast<Painting::PaintableWithLines&>(paintable_box);
                 paintable_with_lines.set_line_boxes(move(used_values.line_boxes));
                 paintables_with_lines.append(paintable_with_lines);
diff --git a/Userland/Libraries/LibWeb/Painting/Paintable.cpp b/Userland/Libraries/LibWeb/Painting/Paintable.cpp
index 88d1ec9d5c..87d6dc70df 100644
--- a/Userland/Libraries/LibWeb/Painting/Paintable.cpp
+++ b/Userland/Libraries/LibWeb/Painting/Paintable.cpp
@@ -79,7 +79,7 @@ Optional<HitTestResult> Paintable::hit_test(CSSPixelPoint, HitTestType) const
 
 StackingContext const* Paintable::stacking_context_rooted_here() const
 {
-    if (!layout_node().is_box())
+    if (!is<PaintableBox>(*this))
         return nullptr;
     return static_cast<PaintableBox const&>(*this).stacking_context();
 }
diff --git a/Userland/Libraries/LibWeb/Painting/Paintable.h b/Userland/Libraries/LibWeb/Painting/Paintable.h
index d3f832d1c3..103374b409 100644
--- a/Userland/Libraries/LibWeb/Painting/Paintable.h
+++ b/Userland/Libraries/LibWeb/Painting/Paintable.h
@@ -154,6 +154,9 @@ public:
     template<typename T>
     bool fast_is() const = delete;
 
+    [[nodiscard]] virtual bool is_paintable_box() const { return false; }
+    [[nodiscard]] virtual bool is_paintable_with_lines() const { return false; }
+
     StackingContext const* stacking_context_rooted_here() const;
 
 protected:
@@ -179,6 +182,9 @@ inline DOM::Node const* HitTestResult::dom_node() const
 }
 
 template<>
-inline bool Paintable::fast_is<PaintableBox>() const { return m_layout_node->is_box(); }
+inline bool Paintable::fast_is<PaintableBox>() const { return is_paintable_box(); }
+
+template<>
+inline bool Paintable::fast_is<PaintableWithLines>() const { return is_paintable_with_lines(); }
 
 }
diff --git a/Userland/Libraries/LibWeb/Painting/PaintableBox.h b/Userland/Libraries/LibWeb/Painting/PaintableBox.h
index d3b94ff66d..9d4f9c85b6 100644
--- a/Userland/Libraries/LibWeb/Painting/PaintableBox.h
+++ b/Userland/Libraries/LibWeb/Painting/PaintableBox.h
@@ -197,6 +197,8 @@ protected:
     Vector<ShadowData> resolve_box_shadow_data() const;
 
 private:
+    [[nodiscard]] virtual bool is_paintable_box() const final { return true; }
+
     Optional<OverflowData> m_overflow_data;
 
     CSSPixelPoint m_offset;
@@ -249,6 +251,8 @@ protected:
     PaintableWithLines(Layout::BlockContainer const&);
 
 private:
+    [[nodiscard]] virtual bool is_paintable_with_lines() const final { return true; }
+
     Vector<Layout::LineBox> m_line_boxes;
 };