diff --git a/Userland/Libraries/LibWeb/CSS/Length.h b/Userland/Libraries/LibWeb/CSS/Length.h
index db84635bd3..ed7335c6a2 100644
--- a/Userland/Libraries/LibWeb/CSS/Length.h
+++ b/Userland/Libraries/LibWeb/CSS/Length.h
@@ -147,3 +147,11 @@ private:
 };
 
 }
+
+template<>
+struct AK::Formatter<Web::CSS::Length> : Formatter<StringView> {
+    ErrorOr<void> format(FormatBuilder& builder, Web::CSS::Length const& length)
+    {
+        return Formatter<StringView>::format(builder, length.to_string());
+    }
+};
diff --git a/Userland/Libraries/LibWeb/CSS/Percentage.h b/Userland/Libraries/LibWeb/CSS/Percentage.h
index 86dce08e6d..74ad35989e 100644
--- a/Userland/Libraries/LibWeb/CSS/Percentage.h
+++ b/Userland/Libraries/LibWeb/CSS/Percentage.h
@@ -139,3 +139,19 @@ public:
 };
 
 }
+
+template<>
+struct AK::Formatter<Web::CSS::Percentage> : Formatter<StringView> {
+    ErrorOr<void> format(FormatBuilder& builder, Web::CSS::Percentage const& percentage)
+    {
+        return Formatter<StringView>::format(builder, percentage.to_string());
+    }
+};
+
+template<>
+struct AK::Formatter<Web::CSS::LengthPercentage> : Formatter<StringView> {
+    ErrorOr<void> format(FormatBuilder& builder, Web::CSS::LengthPercentage const& length_percentage)
+    {
+        return Formatter<StringView>::format(builder, length_percentage.to_string());
+    }
+};