diff --git a/Userland/Libraries/LibWeb/Bindings/CSSStyleDeclarationWrapperCustom.cpp b/Userland/Libraries/LibWeb/Bindings/CSSStyleDeclarationWrapperCustom.cpp
index d5e572fcf3..66bd50f446 100644
--- a/Userland/Libraries/LibWeb/Bindings/CSSStyleDeclarationWrapperCustom.cpp
+++ b/Userland/Libraries/LibWeb/Bindings/CSSStyleDeclarationWrapperCustom.cpp
@@ -44,7 +44,8 @@ bool CSSStyleDeclarationWrapper::internal_set(JS::PropertyName const& name, JS::
     if (vm().exception())
         return false;
 
-    return impl().set_property(property_id, css_text);
+    impl().set_property(property_id, css_text);
+    return true;
 }
 
 }
diff --git a/Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.cpp b/Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.cpp
index dae3a69a59..0635a4c2e3 100644
--- a/Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.cpp
+++ b/Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.cpp
@@ -64,9 +64,12 @@ Optional<StyleProperty> PropertyOwningCSSStyleDeclaration::property(PropertyID p
 bool PropertyOwningCSSStyleDeclaration::set_property(PropertyID property_id, StringView css_text)
 {
     auto new_value = parse_css_value(CSS::ParsingContext {}, css_text, property_id);
-    // FIXME: What are we supposed to do if we can't parse it?
-    if (!new_value)
+    if (!new_value) {
+        m_properties.remove_all_matching([&](auto& entry) {
+            return entry.property_id == property_id;
+        });
         return false;
+    }
 
     ScopeGuard style_invalidation_guard = [&] {
         auto& declaration = verify_cast<CSS::ElementInlineCSSStyleDeclaration>(*this);
@@ -102,4 +105,12 @@ String CSSStyleDeclaration::get_property_value(StringView property_name) const
     return maybe_property->value->to_string();
 }
 
+void CSSStyleDeclaration::set_property(StringView property_name, StringView css_text)
+{
+    auto property_id = property_id_from_string(property_name);
+    if (property_id == CSS::PropertyID::Invalid)
+        return;
+    set_property(property_id, css_text);
+}
+
 }
diff --git a/Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.h b/Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.h
index 17bfcb26c1..37a32c9f6a 100644
--- a/Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.h
+++ b/Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.h
@@ -34,6 +34,8 @@ public:
     virtual Optional<StyleProperty> property(PropertyID) const = 0;
     virtual bool set_property(PropertyID, StringView css_text) = 0;
 
+    void set_property(StringView property_name, StringView css_text);
+
     String get_property_value(StringView property) const;
 
 protected:
diff --git a/Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.idl b/Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.idl
index 743f2151ad..bce8af29f3 100644
--- a/Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.idl
+++ b/Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.idl
@@ -6,4 +6,6 @@ interface CSSStyleDeclaration {
 
     CSSOMString getPropertyValue(CSSOMString property);
 
+    [CEReactions] undefined setProperty(CSSOMString property, [LegacyNullToEmptyString] CSSOMString value);
+
 };