diff --git a/Userland/Libraries/LibWeb/CSS/Identifiers.json b/Userland/Libraries/LibWeb/CSS/Identifiers.json
index 6696b50cbcf..bbeb9aea1e5 100644
--- a/Userland/Libraries/LibWeb/CSS/Identifiers.json
+++ b/Userland/Libraries/LibWeb/CSS/Identifiers.json
@@ -107,6 +107,7 @@
   "lowercase",
   "lower-alpha",
   "lower-latin",
+  "lower-roman",
   "medium",
   "move",
   "ne-resize",
@@ -163,6 +164,7 @@
   "uppercase",
   "upper-alpha",
   "upper-latin",
+  "upper-roman",
   "visible",
   "vertical-text",
   "wait",
diff --git a/Userland/Libraries/LibWeb/CSS/StyleProperties.cpp b/Userland/Libraries/LibWeb/CSS/StyleProperties.cpp
index be62c097f03..e3c9a56222c 100644
--- a/Userland/Libraries/LibWeb/CSS/StyleProperties.cpp
+++ b/Userland/Libraries/LibWeb/CSS/StyleProperties.cpp
@@ -645,6 +645,10 @@ Optional<CSS::ListStyleType> StyleProperties::list_style_type() const
         return CSS::ListStyleType::UpperAlpha;
     case CSS::ValueID::UpperLatin:
         return CSS::ListStyleType::UpperLatin;
+    case CSS::ValueID::UpperRoman:
+        return CSS::ListStyleType::UpperRoman;
+    case CSS::ValueID::LowerRoman:
+        return CSS::ListStyleType::LowerRoman;
     default:
         return {};
     }
diff --git a/Userland/Libraries/LibWeb/CSS/StyleValue.h b/Userland/Libraries/LibWeb/CSS/StyleValue.h
index 00e5002459a..51910ff91c8 100644
--- a/Userland/Libraries/LibWeb/CSS/StyleValue.h
+++ b/Userland/Libraries/LibWeb/CSS/StyleValue.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Tobias Christiansen <tobi@tobyase.de>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -173,8 +174,10 @@ enum class ListStyleType {
     DecimalLeadingZero,
     LowerAlpha,
     LowerLatin,
+    LowerRoman,
     UpperAlpha,
     UpperLatin,
+    UpperRoman,
 };
 
 enum class Overflow : u8 {
diff --git a/Userland/Libraries/LibWeb/Layout/ListItemMarkerBox.cpp b/Userland/Libraries/LibWeb/Layout/ListItemMarkerBox.cpp
index 3833755dadd..7c26770c089 100644
--- a/Userland/Libraries/LibWeb/Layout/ListItemMarkerBox.cpp
+++ b/Userland/Libraries/LibWeb/Layout/ListItemMarkerBox.cpp
@@ -36,6 +36,12 @@ ListItemMarkerBox::ListItemMarkerBox(DOM::Document& document, CSS::ListStyleType
     case CSS::ListStyleType::UpperLatin:
         m_text = String::bijective_base_from(m_index - 1);
         break;
+    case CSS::ListStyleType::LowerRoman:
+        m_text = String::roman_number_from(m_index).to_lowercase();
+        break;
+    case CSS::ListStyleType::UpperRoman:
+        m_text = String::roman_number_from(m_index);
+        break;
     case CSS::ListStyleType::None:
         break;
 
@@ -88,8 +94,10 @@ void ListItemMarkerBox::paint(PaintContext& context, PaintPhase phase)
     case CSS::ListStyleType::DecimalLeadingZero:
     case CSS::ListStyleType::LowerAlpha:
     case CSS::ListStyleType::LowerLatin:
+    case CSS::ListStyleType::LowerRoman:
     case CSS::ListStyleType::UpperAlpha:
     case CSS::ListStyleType::UpperLatin:
+    case CSS::ListStyleType::UpperRoman:
         if (m_text.is_null())
             break;
         context.painter().draw_text(enclosing, m_text, Gfx::TextAlignment::Center);