diff --git a/Userland/Libraries/LibWeb/CSS/Parser/DeclarationOrAtRule.cpp b/Userland/Libraries/LibWeb/CSS/Parser/DeclarationOrAtRule.cpp
index cee9589a9e..3c429787c2 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/DeclarationOrAtRule.cpp
+++ b/Userland/Libraries/LibWeb/CSS/Parser/DeclarationOrAtRule.cpp
@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2020-2021, the SerenityOS developers.
- * Copyright (c) 2021-2022, Sam Atkins <atkinssj@serenityos.org>
+ * Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -24,20 +24,4 @@ DeclarationOrAtRule::DeclarationOrAtRule(Declaration declaration)
 
 DeclarationOrAtRule::~DeclarationOrAtRule() = default;
 
-DeprecatedString DeclarationOrAtRule::to_deprecated_string() const
-{
-    StringBuilder builder;
-    switch (m_type) {
-    default:
-    case DeclarationType::At:
-        builder.append(m_at->to_deprecated_string());
-        break;
-    case DeclarationType::Declaration:
-        builder.append(m_declaration->to_string().release_value_but_fixme_should_propagate_errors());
-        break;
-    }
-
-    return builder.to_deprecated_string();
-}
-
 }
diff --git a/Userland/Libraries/LibWeb/CSS/Parser/DeclarationOrAtRule.h b/Userland/Libraries/LibWeb/CSS/Parser/DeclarationOrAtRule.h
index d0d6ced460..2a839fc767 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/DeclarationOrAtRule.h
+++ b/Userland/Libraries/LibWeb/CSS/Parser/DeclarationOrAtRule.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2020-2021, the SerenityOS developers.
+ * Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -37,8 +38,6 @@ public:
         return *m_declaration;
     }
 
-    DeprecatedString to_deprecated_string() const;
-
 private:
     DeclarationType m_type;
     RefPtr<Rule> m_at;
diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
index ebcee80605..d3f852cfa8 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
@@ -1518,7 +1518,7 @@ NonnullRefPtr<Rule> Parser::consume_an_at_rule(TokenStream<T>& tokens)
 
     // Create a new at-rule with its name set to the value of the current input token, its prelude initially set to an empty list, and its value initially set to nothing.
     // NOTE: We create the Rule fully initialized when we return it instead.
-    DeprecatedFlyString at_rule_name = ((Token)name_ident).at_keyword();
+    auto at_rule_name = FlyString::from_utf8(((Token)name_ident).at_keyword()).release_value_but_fixme_should_propagate_errors();
     Vector<ComponentValue> prelude;
     RefPtr<Block> block;
 
diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Rule.cpp b/Userland/Libraries/LibWeb/CSS/Parser/Rule.cpp
index 9e22b28459..55a07eeac4 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Rule.cpp
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Rule.cpp
@@ -1,16 +1,15 @@
 /*
  * Copyright (c) 2020-2021, the SerenityOS developers.
- * Copyright (c) 2021-2022, Sam Atkins <atkinssj@serenityos.org>
+ * Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #include <LibWeb/CSS/Parser/Rule.h>
-#include <LibWeb/CSS/Serialize.h>
 
 namespace Web::CSS::Parser {
 
-Rule::Rule(Rule::Type type, DeprecatedFlyString name, Vector<ComponentValue> prelude, RefPtr<Block> block)
+Rule::Rule(Rule::Type type, FlyString name, Vector<ComponentValue> prelude, RefPtr<Block> block)
     : m_type(type)
     , m_at_rule_name(move(name))
     , m_prelude(move(prelude))
@@ -20,23 +19,4 @@ Rule::Rule(Rule::Type type, DeprecatedFlyString name, Vector<ComponentValue> pre
 
 Rule::~Rule() = default;
 
-DeprecatedString Rule::to_deprecated_string() const
-{
-    StringBuilder builder;
-
-    if (is_at_rule()) {
-        builder.append('@');
-        serialize_an_identifier(builder, m_at_rule_name);
-    }
-
-    builder.join(' ', m_prelude);
-
-    if (m_block)
-        builder.append(m_block->to_string().release_value_but_fixme_should_propagate_errors());
-    else
-        builder.append(';');
-
-    return builder.to_deprecated_string();
-}
-
 }
diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Rule.h b/Userland/Libraries/LibWeb/CSS/Parser/Rule.h
index dfc9a7f895..60647a7b41 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Rule.h
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Rule.h
@@ -1,13 +1,13 @@
 /*
  * Copyright (c) 2020-2021, the SerenityOS developers.
- * Copyright (c) 2021, Sam Atkins <atkinssj@serenityos.org>
+ * Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #pragma once
 
-#include <AK/DeprecatedFlyString.h>
+#include <AK/FlyString.h>
 #include <AK/RefCounted.h>
 #include <AK/Vector.h>
 #include <LibWeb/CSS/Parser/Block.h>
@@ -22,7 +22,7 @@ public:
         Qualified,
     };
 
-    static NonnullRefPtr<Rule> make_at_rule(DeprecatedFlyString name, Vector<ComponentValue> prelude, RefPtr<Block> block)
+    static NonnullRefPtr<Rule> make_at_rule(FlyString name, Vector<ComponentValue> prelude, RefPtr<Block> block)
     {
         return adopt_ref(*new Rule(Type::At, move(name), move(prelude), move(block)));
     }
@@ -41,13 +41,11 @@ public:
     RefPtr<Block const> block() const { return m_block; }
     StringView at_rule_name() const { return m_at_rule_name; }
 
-    DeprecatedString to_deprecated_string() const;
-
 private:
-    Rule(Type, DeprecatedFlyString name, Vector<ComponentValue> prelude, RefPtr<Block>);
+    Rule(Type, FlyString name, Vector<ComponentValue> prelude, RefPtr<Block>);
 
     Type const m_type;
-    DeprecatedFlyString m_at_rule_name;
+    FlyString m_at_rule_name;
     Vector<ComponentValue> m_prelude;
     RefPtr<Block> m_block;
 };