diff --git a/Libraries/LibWeb/CMakeLists.txt b/Libraries/LibWeb/CMakeLists.txt
index 26d4d4f922..4db612d553 100644
--- a/Libraries/LibWeb/CMakeLists.txt
+++ b/Libraries/LibWeb/CMakeLists.txt
@@ -91,6 +91,7 @@ set(SOURCES
     CSS/CSS.cpp
     CSS/CSSAnimation.cpp
     CSS/CSSConditionRule.cpp
+    CSS/CSSCounterStyleRule.cpp
     CSS/CSSDescriptors.cpp
     CSS/CSSFontFaceDescriptors.cpp
     CSS/CSSFontFaceRule.cpp
diff --git a/Libraries/LibWeb/CSS/CSSCounterStyleRule.cpp b/Libraries/LibWeb/CSS/CSSCounterStyleRule.cpp
new file mode 100644
index 0000000000..25b7b805e7
--- /dev/null
+++ b/Libraries/LibWeb/CSS/CSSCounterStyleRule.cpp
@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2025, Jelle Raaijmakers <jelle@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/Bindings/CSSCounterStyleRulePrototype.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/CSS/CSSCounterStyleRule.h>
+
+namespace Web::CSS {
+
+CSSCounterStyleRule::CSSCounterStyleRule(JS::Realm& realm, Type type)
+    : CSSRule(realm, type)
+{
+}
+
+void CSSCounterStyleRule::initialize(JS::Realm& realm)
+{
+    WEB_SET_PROTOTYPE_FOR_INTERFACE(CSSCounterStyleRule);
+    Base::initialize(realm);
+}
+
+}
diff --git a/Libraries/LibWeb/CSS/CSSCounterStyleRule.h b/Libraries/LibWeb/CSS/CSSCounterStyleRule.h
new file mode 100644
index 0000000000..6cf4dbabc5
--- /dev/null
+++ b/Libraries/LibWeb/CSS/CSSCounterStyleRule.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2025, Jelle Raaijmakers <jelle@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/CSS/CSSRule.h>
+
+namespace Web::CSS {
+
+class CSSCounterStyleRule : public CSSRule {
+    WEB_PLATFORM_OBJECT(CSSCounterStyleRule, CSSRule);
+
+public:
+    virtual ~CSSCounterStyleRule() = default;
+
+protected:
+    CSSCounterStyleRule(JS::Realm&, Type);
+
+    virtual void initialize(JS::Realm&) override;
+};
+
+}
diff --git a/Libraries/LibWeb/CSS/CSSCounterStyleRule.idl b/Libraries/LibWeb/CSS/CSSCounterStyleRule.idl
new file mode 100644
index 0000000000..f6333a3ed6
--- /dev/null
+++ b/Libraries/LibWeb/CSS/CSSCounterStyleRule.idl
@@ -0,0 +1,17 @@
+#import <CSS/CSSRule.idl>
+
+// https://drafts.csswg.org/css-counter-styles/#the-csscounterstylerule-interface
+[Exposed=Window]
+interface CSSCounterStyleRule : CSSRule {
+    [FIXME] attribute CSSOMString name;
+    [FIXME] attribute CSSOMString system;
+    [FIXME] attribute CSSOMString symbols;
+    [FIXME] attribute CSSOMString additiveSymbols;
+    [FIXME] attribute CSSOMString negative;
+    [FIXME] attribute CSSOMString prefix;
+    [FIXME] attribute CSSOMString suffix;
+    [FIXME] attribute CSSOMString range;
+    [FIXME] attribute CSSOMString pad;
+    [FIXME] attribute CSSOMString speakAs;
+    [FIXME] attribute CSSOMString fallback;
+};
diff --git a/Libraries/LibWeb/CSS/CSSRule.h b/Libraries/LibWeb/CSS/CSSRule.h
index aeeb124261..0055830798 100644
--- a/Libraries/LibWeb/CSS/CSSRule.h
+++ b/Libraries/LibWeb/CSS/CSSRule.h
@@ -63,7 +63,7 @@ public:
     virtual void clear_caches();
 
 protected:
-    explicit CSSRule(JS::Realm&, Type);
+    CSSRule(JS::Realm&, Type);
 
     virtual void visit_edges(Cell::Visitor&) override;
 
diff --git a/Libraries/LibWeb/idl_files.cmake b/Libraries/LibWeb/idl_files.cmake
index 5fa1d46334..a2f04c610c 100644
--- a/Libraries/LibWeb/idl_files.cmake
+++ b/Libraries/LibWeb/idl_files.cmake
@@ -23,6 +23,7 @@ libweb_js_bindings(Crypto/SubtleCrypto)
 libweb_js_bindings(CSS/AnimationEvent)
 libweb_js_bindings(CSS/CSSAnimation)
 libweb_js_bindings(CSS/CSSConditionRule)
+libweb_js_bindings(CSS/CSSCounterStyleRule)
 libweb_js_bindings(CSS/CSSFontFaceDescriptors)
 libweb_js_bindings(CSS/CSSFontFaceRule)
 libweb_js_bindings(CSS/CSSGroupingRule)
diff --git a/Tests/LibWeb/Text/expected/all-window-properties.txt b/Tests/LibWeb/Text/expected/all-window-properties.txt
index b6685611e1..a79498ab37 100644
--- a/Tests/LibWeb/Text/expected/all-window-properties.txt
+++ b/Tests/LibWeb/Text/expected/all-window-properties.txt
@@ -38,6 +38,7 @@ ByteLengthQueuingStrategy
 CDATASection
 CSSAnimation
 CSSConditionRule
+CSSCounterStyleRule
 CSSFontFaceDescriptors
 CSSFontFaceRule
 CSSGroupingRule