diff --git a/Userland/Libraries/LibWeb/CSS/ResolvedCSSStyleDeclaration.cpp b/Userland/Libraries/LibWeb/CSS/ResolvedCSSStyleDeclaration.cpp
index 1ad7322c97..89dbc77f35 100644
--- a/Userland/Libraries/LibWeb/CSS/ResolvedCSSStyleDeclaration.cpp
+++ b/Userland/Libraries/LibWeb/CSS/ResolvedCSSStyleDeclaration.cpp
@@ -452,14 +452,22 @@ RefPtr<StyleValue> ResolvedCSSStyleDeclaration::style_value_for_property(Layout:
     case CSS::PropertyID::Width:
         return LengthStyleValue::create(layout_node.computed_values().width());
     case CSS::PropertyID::MinWidth:
+        if (layout_node.computed_values().min_width().is_undefined())
+            return IdentifierStyleValue::create(CSS::ValueID::None);
         return LengthStyleValue::create(layout_node.computed_values().min_width());
     case CSS::PropertyID::MaxWidth:
+        if (layout_node.computed_values().max_width().is_undefined())
+            return IdentifierStyleValue::create(CSS::ValueID::None);
         return LengthStyleValue::create(layout_node.computed_values().max_width());
     case CSS::PropertyID::Height:
         return LengthStyleValue::create(layout_node.computed_values().height());
     case CSS::PropertyID::MinHeight:
+        if (layout_node.computed_values().min_height().is_undefined())
+            return IdentifierStyleValue::create(CSS::ValueID::None);
         return LengthStyleValue::create(layout_node.computed_values().min_height());
     case CSS::PropertyID::MaxHeight:
+        if (layout_node.computed_values().max_height().is_undefined())
+            return IdentifierStyleValue::create(CSS::ValueID::None);
         return LengthStyleValue::create(layout_node.computed_values().max_height());
     case CSS::PropertyID::MarginTop:
         return LengthStyleValue::create(layout_node.computed_values().margin().top);