From 503d41d02d5d8ea1c701f22b2b6d10d305030e29 Mon Sep 17 00:00:00 2001
From: Sam Atkins <sam@ladybird.org>
Date: Tue, 12 Aug 2025 11:58:17 +0100
Subject: [PATCH] LibWeb/CSS: Implement the `:heading`/`:heading()`
 pseudo-class

Corresponds to part of
https://github.com/whatwg/html/commit/65dc095e44436d81316856aaf3c448c7c083ae16
---
 Libraries/LibWeb/CSS/PseudoClasses.json       |   3 +
 Libraries/LibWeb/CSS/SelectorEngine.cpp       |  39 +++
 .../wpt-import/css/selectors/heading.txt      | 313 ++++++++++++++++++
 .../wpt-import/css/selectors/heading.html     |  67 ++++
 4 files changed, 422 insertions(+)
 create mode 100644 Tests/LibWeb/Text/expected/wpt-import/css/selectors/heading.txt
 create mode 100644 Tests/LibWeb/Text/input/wpt-import/css/selectors/heading.html

diff --git a/Libraries/LibWeb/CSS/PseudoClasses.json b/Libraries/LibWeb/CSS/PseudoClasses.json
index 4c3f43e42d8..4048796dddb 100644
--- a/Libraries/LibWeb/CSS/PseudoClasses.json
+++ b/Libraries/LibWeb/CSS/PseudoClasses.json
@@ -50,6 +50,9 @@
   "has": {
     "argument": "<relative-selector-list>"
   },
+  "heading": {
+    "argument": "<an+b>#?"
+  },
   "high-value": {
     "argument": ""
   },
diff --git a/Libraries/LibWeb/CSS/SelectorEngine.cpp b/Libraries/LibWeb/CSS/SelectorEngine.cpp
index d6d0fa9acc2..30f67d1f864 100644
--- a/Libraries/LibWeb/CSS/SelectorEngine.cpp
+++ b/Libraries/LibWeb/CSS/SelectorEngine.cpp
@@ -1032,6 +1032,45 @@ static inline bool matches_pseudo_class(CSS::Selector::SimpleSelector::PseudoCla
             return custom_state_set->has_state(pseudo_class.ident->string_value);
         return false;
     }
+    case CSS::PseudoClass::Heading: {
+        // https://html.spec.whatwg.org/multipage/semantics-other.html#selector-heading
+        // The :heading pseudo-class must match all h1, h2, h3, h4, h5, and h6 elements.
+
+        // https://html.spec.whatwg.org/multipage/semantics-other.html#selector-heading-functional
+        // The :heading(An+B#) pseudo-class must match all h1, h2, h3, h4, h5, and h6 elements that have a heading level among An+B. [CSSSYNTAX] [CSSVALUES]
+
+        // NB: We combine the "is this an h* element?" and "what is it's level?" checks together here.
+        if (!element.is_html_element())
+            return false;
+        auto heading_level = [](auto& local_name) -> Optional<int> {
+            if (local_name == HTML::TagNames::h1)
+                return 1;
+            if (local_name == HTML::TagNames::h2)
+                return 2;
+            if (local_name == HTML::TagNames::h3)
+                return 3;
+            if (local_name == HTML::TagNames::h4)
+                return 4;
+            if (local_name == HTML::TagNames::h5)
+                return 5;
+            if (local_name == HTML::TagNames::h6)
+                return 6;
+            return {};
+        }(element.lowercased_local_name());
+
+        if (!heading_level.has_value())
+            return false;
+
+        if (pseudo_class.an_plus_b_patterns.is_empty())
+            return true;
+
+        for (auto const& an_plus_b_pattern : pseudo_class.an_plus_b_patterns) {
+            if (an_plus_b_pattern.matches(heading_level.value()))
+                return true;
+        }
+
+        return false;
+    }
     }
 
     return false;
diff --git a/Tests/LibWeb/Text/expected/wpt-import/css/selectors/heading.txt b/Tests/LibWeb/Text/expected/wpt-import/css/selectors/heading.txt
new file mode 100644
index 00000000000..ac3cfcad8d7
--- /dev/null
+++ b/Tests/LibWeb/Text/expected/wpt-import/css/selectors/heading.txt
@@ -0,0 +1,313 @@
+Harness status: OK
+
+Found 308 tests
+
+308 Pass
+Pass	<h1 data-expect-match="1"></h1> :heading
+Pass	<h1 data-expect-match="1"></h1> :heading(1)
+Pass	<h1 data-expect-match="1"></h1> :heading(2)
+Pass	<h1 data-expect-match="1"></h1> :heading(3)
+Pass	<h1 data-expect-match="1"></h1> :heading(4)
+Pass	<h1 data-expect-match="1"></h1> :heading(5)
+Pass	<h1 data-expect-match="1"></h1> :heading(6)
+Pass	<h1 data-expect-match="1"></h1> :heading(7)
+Pass	<h1 data-expect-match="1"></h1> :heading(8)
+Pass	<h1 data-expect-match="1"></h1> :heading(9)
+Pass	<h1 data-expect-match="1"></h1> :heading(0)
+Pass	<h1 data-expect-match="1"></h1> :heading(-1)
+Pass	<h1 data-expect-match="1"></h1> :heading(0, 1, 2)
+Pass	<h1 data-expect-match="1"></h1> :heading(6, 7)
+Pass	<h1 data-expect-match="1"></h1> :heading(n)
+Pass	<h1 data-expect-match="1"></h1> :heading(2n)
+Pass	<h1 data-expect-match="1"></h1> :heading(2n+1)
+Pass	<h1 data-expect-match="1"></h1> :heading(2n+2)
+Pass	<h1 data-expect-match="1"></h1> :heading(-n+3)
+Pass	<h1 data-expect-match="1"></h1> :heading(2n, 3n)
+Pass	<h1 data-expect-match="1"></h1> :heading(even)
+Pass	<h1 data-expect-match="1"></h1> :heading(odd)
+Pass	<h2 data-expect-match="2"></h2> :heading
+Pass	<h2 data-expect-match="2"></h2> :heading(1)
+Pass	<h2 data-expect-match="2"></h2> :heading(2)
+Pass	<h2 data-expect-match="2"></h2> :heading(3)
+Pass	<h2 data-expect-match="2"></h2> :heading(4)
+Pass	<h2 data-expect-match="2"></h2> :heading(5)
+Pass	<h2 data-expect-match="2"></h2> :heading(6)
+Pass	<h2 data-expect-match="2"></h2> :heading(7)
+Pass	<h2 data-expect-match="2"></h2> :heading(8)
+Pass	<h2 data-expect-match="2"></h2> :heading(9)
+Pass	<h2 data-expect-match="2"></h2> :heading(0)
+Pass	<h2 data-expect-match="2"></h2> :heading(-1)
+Pass	<h2 data-expect-match="2"></h2> :heading(0, 1, 2)
+Pass	<h2 data-expect-match="2"></h2> :heading(6, 7)
+Pass	<h2 data-expect-match="2"></h2> :heading(n)
+Pass	<h2 data-expect-match="2"></h2> :heading(2n)
+Pass	<h2 data-expect-match="2"></h2> :heading(2n+1)
+Pass	<h2 data-expect-match="2"></h2> :heading(2n+2)
+Pass	<h2 data-expect-match="2"></h2> :heading(-n+3)
+Pass	<h2 data-expect-match="2"></h2> :heading(2n, 3n)
+Pass	<h2 data-expect-match="2"></h2> :heading(even)
+Pass	<h2 data-expect-match="2"></h2> :heading(odd)
+Pass	<h3 data-expect-match="3"></h3> :heading
+Pass	<h3 data-expect-match="3"></h3> :heading(1)
+Pass	<h3 data-expect-match="3"></h3> :heading(2)
+Pass	<h3 data-expect-match="3"></h3> :heading(3)
+Pass	<h3 data-expect-match="3"></h3> :heading(4)
+Pass	<h3 data-expect-match="3"></h3> :heading(5)
+Pass	<h3 data-expect-match="3"></h3> :heading(6)
+Pass	<h3 data-expect-match="3"></h3> :heading(7)
+Pass	<h3 data-expect-match="3"></h3> :heading(8)
+Pass	<h3 data-expect-match="3"></h3> :heading(9)
+Pass	<h3 data-expect-match="3"></h3> :heading(0)
+Pass	<h3 data-expect-match="3"></h3> :heading(-1)
+Pass	<h3 data-expect-match="3"></h3> :heading(0, 1, 2)
+Pass	<h3 data-expect-match="3"></h3> :heading(6, 7)
+Pass	<h3 data-expect-match="3"></h3> :heading(n)
+Pass	<h3 data-expect-match="3"></h3> :heading(2n)
+Pass	<h3 data-expect-match="3"></h3> :heading(2n+1)
+Pass	<h3 data-expect-match="3"></h3> :heading(2n+2)
+Pass	<h3 data-expect-match="3"></h3> :heading(-n+3)
+Pass	<h3 data-expect-match="3"></h3> :heading(2n, 3n)
+Pass	<h3 data-expect-match="3"></h3> :heading(even)
+Pass	<h3 data-expect-match="3"></h3> :heading(odd)
+Pass	<h4 data-expect-match="4"></h4> :heading
+Pass	<h4 data-expect-match="4"></h4> :heading(1)
+Pass	<h4 data-expect-match="4"></h4> :heading(2)
+Pass	<h4 data-expect-match="4"></h4> :heading(3)
+Pass	<h4 data-expect-match="4"></h4> :heading(4)
+Pass	<h4 data-expect-match="4"></h4> :heading(5)
+Pass	<h4 data-expect-match="4"></h4> :heading(6)
+Pass	<h4 data-expect-match="4"></h4> :heading(7)
+Pass	<h4 data-expect-match="4"></h4> :heading(8)
+Pass	<h4 data-expect-match="4"></h4> :heading(9)
+Pass	<h4 data-expect-match="4"></h4> :heading(0)
+Pass	<h4 data-expect-match="4"></h4> :heading(-1)
+Pass	<h4 data-expect-match="4"></h4> :heading(0, 1, 2)
+Pass	<h4 data-expect-match="4"></h4> :heading(6, 7)
+Pass	<h4 data-expect-match="4"></h4> :heading(n)
+Pass	<h4 data-expect-match="4"></h4> :heading(2n)
+Pass	<h4 data-expect-match="4"></h4> :heading(2n+1)
+Pass	<h4 data-expect-match="4"></h4> :heading(2n+2)
+Pass	<h4 data-expect-match="4"></h4> :heading(-n+3)
+Pass	<h4 data-expect-match="4"></h4> :heading(2n, 3n)
+Pass	<h4 data-expect-match="4"></h4> :heading(even)
+Pass	<h4 data-expect-match="4"></h4> :heading(odd)
+Pass	<h5 data-expect-match="5"></h5> :heading
+Pass	<h5 data-expect-match="5"></h5> :heading(1)
+Pass	<h5 data-expect-match="5"></h5> :heading(2)
+Pass	<h5 data-expect-match="5"></h5> :heading(3)
+Pass	<h5 data-expect-match="5"></h5> :heading(4)
+Pass	<h5 data-expect-match="5"></h5> :heading(5)
+Pass	<h5 data-expect-match="5"></h5> :heading(6)
+Pass	<h5 data-expect-match="5"></h5> :heading(7)
+Pass	<h5 data-expect-match="5"></h5> :heading(8)
+Pass	<h5 data-expect-match="5"></h5> :heading(9)
+Pass	<h5 data-expect-match="5"></h5> :heading(0)
+Pass	<h5 data-expect-match="5"></h5> :heading(-1)
+Pass	<h5 data-expect-match="5"></h5> :heading(0, 1, 2)
+Pass	<h5 data-expect-match="5"></h5> :heading(6, 7)
+Pass	<h5 data-expect-match="5"></h5> :heading(n)
+Pass	<h5 data-expect-match="5"></h5> :heading(2n)
+Pass	<h5 data-expect-match="5"></h5> :heading(2n+1)
+Pass	<h5 data-expect-match="5"></h5> :heading(2n+2)
+Pass	<h5 data-expect-match="5"></h5> :heading(-n+3)
+Pass	<h5 data-expect-match="5"></h5> :heading(2n, 3n)
+Pass	<h5 data-expect-match="5"></h5> :heading(even)
+Pass	<h5 data-expect-match="5"></h5> :heading(odd)
+Pass	<h6 data-expect-match="6"></h6> :heading
+Pass	<h6 data-expect-match="6"></h6> :heading(1)
+Pass	<h6 data-expect-match="6"></h6> :heading(2)
+Pass	<h6 data-expect-match="6"></h6> :heading(3)
+Pass	<h6 data-expect-match="6"></h6> :heading(4)
+Pass	<h6 data-expect-match="6"></h6> :heading(5)
+Pass	<h6 data-expect-match="6"></h6> :heading(6)
+Pass	<h6 data-expect-match="6"></h6> :heading(7)
+Pass	<h6 data-expect-match="6"></h6> :heading(8)
+Pass	<h6 data-expect-match="6"></h6> :heading(9)
+Pass	<h6 data-expect-match="6"></h6> :heading(0)
+Pass	<h6 data-expect-match="6"></h6> :heading(-1)
+Pass	<h6 data-expect-match="6"></h6> :heading(0, 1, 2)
+Pass	<h6 data-expect-match="6"></h6> :heading(6, 7)
+Pass	<h6 data-expect-match="6"></h6> :heading(n)
+Pass	<h6 data-expect-match="6"></h6> :heading(2n)
+Pass	<h6 data-expect-match="6"></h6> :heading(2n+1)
+Pass	<h6 data-expect-match="6"></h6> :heading(2n+2)
+Pass	<h6 data-expect-match="6"></h6> :heading(-n+3)
+Pass	<h6 data-expect-match="6"></h6> :heading(2n, 3n)
+Pass	<h6 data-expect-match="6"></h6> :heading(even)
+Pass	<h6 data-expect-match="6"></h6> :heading(odd)
+Pass	<h7 data-expect-match=""></h7> :heading
+Pass	<h7 data-expect-match=""></h7> :heading(1)
+Pass	<h7 data-expect-match=""></h7> :heading(2)
+Pass	<h7 data-expect-match=""></h7> :heading(3)
+Pass	<h7 data-expect-match=""></h7> :heading(4)
+Pass	<h7 data-expect-match=""></h7> :heading(5)
+Pass	<h7 data-expect-match=""></h7> :heading(6)
+Pass	<h7 data-expect-match=""></h7> :heading(7)
+Pass	<h7 data-expect-match=""></h7> :heading(8)
+Pass	<h7 data-expect-match=""></h7> :heading(9)
+Pass	<h7 data-expect-match=""></h7> :heading(0)
+Pass	<h7 data-expect-match=""></h7> :heading(-1)
+Pass	<h7 data-expect-match=""></h7> :heading(0, 1, 2)
+Pass	<h7 data-expect-match=""></h7> :heading(6, 7)
+Pass	<h7 data-expect-match=""></h7> :heading(n)
+Pass	<h7 data-expect-match=""></h7> :heading(2n)
+Pass	<h7 data-expect-match=""></h7> :heading(2n+1)
+Pass	<h7 data-expect-match=""></h7> :heading(2n+2)
+Pass	<h7 data-expect-match=""></h7> :heading(-n+3)
+Pass	<h7 data-expect-match=""></h7> :heading(2n, 3n)
+Pass	<h7 data-expect-match=""></h7> :heading(even)
+Pass	<h7 data-expect-match=""></h7> :heading(odd)
+Pass	<h8 data-expect-match=""></h8> :heading
+Pass	<h8 data-expect-match=""></h8> :heading(1)
+Pass	<h8 data-expect-match=""></h8> :heading(2)
+Pass	<h8 data-expect-match=""></h8> :heading(3)
+Pass	<h8 data-expect-match=""></h8> :heading(4)
+Pass	<h8 data-expect-match=""></h8> :heading(5)
+Pass	<h8 data-expect-match=""></h8> :heading(6)
+Pass	<h8 data-expect-match=""></h8> :heading(7)
+Pass	<h8 data-expect-match=""></h8> :heading(8)
+Pass	<h8 data-expect-match=""></h8> :heading(9)
+Pass	<h8 data-expect-match=""></h8> :heading(0)
+Pass	<h8 data-expect-match=""></h8> :heading(-1)
+Pass	<h8 data-expect-match=""></h8> :heading(0, 1, 2)
+Pass	<h8 data-expect-match=""></h8> :heading(6, 7)
+Pass	<h8 data-expect-match=""></h8> :heading(n)
+Pass	<h8 data-expect-match=""></h8> :heading(2n)
+Pass	<h8 data-expect-match=""></h8> :heading(2n+1)
+Pass	<h8 data-expect-match=""></h8> :heading(2n+2)
+Pass	<h8 data-expect-match=""></h8> :heading(-n+3)
+Pass	<h8 data-expect-match=""></h8> :heading(2n, 3n)
+Pass	<h8 data-expect-match=""></h8> :heading(even)
+Pass	<h8 data-expect-match=""></h8> :heading(odd)
+Pass	<h9 data-expect-match=""></h9> :heading
+Pass	<h9 data-expect-match=""></h9> :heading(1)
+Pass	<h9 data-expect-match=""></h9> :heading(2)
+Pass	<h9 data-expect-match=""></h9> :heading(3)
+Pass	<h9 data-expect-match=""></h9> :heading(4)
+Pass	<h9 data-expect-match=""></h9> :heading(5)
+Pass	<h9 data-expect-match=""></h9> :heading(6)
+Pass	<h9 data-expect-match=""></h9> :heading(7)
+Pass	<h9 data-expect-match=""></h9> :heading(8)
+Pass	<h9 data-expect-match=""></h9> :heading(9)
+Pass	<h9 data-expect-match=""></h9> :heading(0)
+Pass	<h9 data-expect-match=""></h9> :heading(-1)
+Pass	<h9 data-expect-match=""></h9> :heading(0, 1, 2)
+Pass	<h9 data-expect-match=""></h9> :heading(6, 7)
+Pass	<h9 data-expect-match=""></h9> :heading(n)
+Pass	<h9 data-expect-match=""></h9> :heading(2n)
+Pass	<h9 data-expect-match=""></h9> :heading(2n+1)
+Pass	<h9 data-expect-match=""></h9> :heading(2n+2)
+Pass	<h9 data-expect-match=""></h9> :heading(-n+3)
+Pass	<h9 data-expect-match=""></h9> :heading(2n, 3n)
+Pass	<h9 data-expect-match=""></h9> :heading(even)
+Pass	<h9 data-expect-match=""></h9> :heading(odd)
+Pass	<h0 data-expect-match=""></h0> :heading
+Pass	<h0 data-expect-match=""></h0> :heading(1)
+Pass	<h0 data-expect-match=""></h0> :heading(2)
+Pass	<h0 data-expect-match=""></h0> :heading(3)
+Pass	<h0 data-expect-match=""></h0> :heading(4)
+Pass	<h0 data-expect-match=""></h0> :heading(5)
+Pass	<h0 data-expect-match=""></h0> :heading(6)
+Pass	<h0 data-expect-match=""></h0> :heading(7)
+Pass	<h0 data-expect-match=""></h0> :heading(8)
+Pass	<h0 data-expect-match=""></h0> :heading(9)
+Pass	<h0 data-expect-match=""></h0> :heading(0)
+Pass	<h0 data-expect-match=""></h0> :heading(-1)
+Pass	<h0 data-expect-match=""></h0> :heading(0, 1, 2)
+Pass	<h0 data-expect-match=""></h0> :heading(6, 7)
+Pass	<h0 data-expect-match=""></h0> :heading(n)
+Pass	<h0 data-expect-match=""></h0> :heading(2n)
+Pass	<h0 data-expect-match=""></h0> :heading(2n+1)
+Pass	<h0 data-expect-match=""></h0> :heading(2n+2)
+Pass	<h0 data-expect-match=""></h0> :heading(-n+3)
+Pass	<h0 data-expect-match=""></h0> :heading(2n, 3n)
+Pass	<h0 data-expect-match=""></h0> :heading(even)
+Pass	<h0 data-expect-match=""></h0> :heading(odd)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(1)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(2)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(3)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(4)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(5)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(6)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(7)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(8)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(9)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(0)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(-1)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(0, 1, 2)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(6, 7)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(n)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(2n)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(2n+1)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(2n+2)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(-n+3)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(2n, 3n)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(even)
+Pass	<h1 data-expect-match="1" aria-level="2"></h1> :heading(odd)
+Pass	<h1 data-expect-match="1"></h1> in section :heading
+Pass	<h1 data-expect-match="1"></h1> in section :heading(1)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(2)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(3)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(4)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(5)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(6)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(7)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(8)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(9)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(0)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(-1)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(0, 1, 2)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(6, 7)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(n)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(2n)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(2n+1)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(2n+2)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(-n+3)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(2n, 3n)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(even)
+Pass	<h1 data-expect-match="1"></h1> in section :heading(odd)
+Pass	<hgroup data-expect-match=""></hgroup> :heading
+Pass	<hgroup data-expect-match=""></hgroup> :heading(1)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(2)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(3)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(4)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(5)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(6)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(7)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(8)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(9)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(0)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(-1)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(0, 1, 2)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(6, 7)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(n)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(2n)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(2n+1)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(2n+2)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(-n+3)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(2n, 3n)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(even)
+Pass	<hgroup data-expect-match=""></hgroup> :heading(odd)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(1)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(2)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(3)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(4)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(5)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(6)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(7)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(8)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(9)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(0)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(-1)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(0, 1, 2)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(6, 7)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(n)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(2n)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(2n+1)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(2n+2)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(-n+3)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(2n, 3n)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(even)
+Pass	<p role="heading" aria-level="1" data-expect-match=""></p> :heading(odd)
\ No newline at end of file
diff --git a/Tests/LibWeb/Text/input/wpt-import/css/selectors/heading.html b/Tests/LibWeb/Text/input/wpt-import/css/selectors/heading.html
new file mode 100644
index 00000000000..5165474b2ff
--- /dev/null
+++ b/Tests/LibWeb/Text/input/wpt-import/css/selectors/heading.html
@@ -0,0 +1,67 @@
+<!doctype html>
+<meta charset=utf-8>
+<title>:heading and :heading() pseudo-classes</title>
+<link rel="help" href="https://drafts.csswg.org/selectors-5/#headings">
+<script src="../../resources/testharness.js"></script>
+<script src="../../resources/testharnessreport.js"></script>
+
+<h1 data-expect-match="1"></h1>
+<h2 data-expect-match="2"></h2>
+<h3 data-expect-match="3"></h3>
+<h4 data-expect-match="4"></h4>
+<h5 data-expect-match="5"></h5>
+<h6 data-expect-match="6"></h6>
+<h7 data-expect-match=""></h7>
+<h8 data-expect-match=""></h8>
+<h9 data-expect-match=""></h9>
+<h0 data-expect-match=""></h0>
+<h1 data-expect-match="1" aria-level="2"></h1>
+<section><h1 data-expect-match="1"></h1></section>
+<hgroup data-expect-match=""></hgroup>
+<p role="heading" aria-level="1" data-expect-match=""></p>
+
+<script>
+const els = document.querySelectorAll('[data-expect-match]');
+const tests = [
+  {args: ['1'], match: [1]},
+  {args: ['2'], match: [2]},
+  {args: ['3'], match: [3]},
+  {args: ['4'], match: [4]},
+  {args: ['5'], match: [5]},
+  {args: ['6'], match: [6]},
+  {args: ['7'], match: []},
+  {args: ['8'], match: []},
+  {args: ['9'], match: []},
+  {args: ['0'], match: []},
+  {args: ['-1'], match: []},
+  {args: ['0', '1', '2'], match: [1, 2]},
+  {args: ['6', '7'], match: [6]},
+  {args: ['n'], match: [1, 2, 3, 4, 5, 6]},
+  {args: ['2n'], match: [2, 4, 6]},
+  {args: ['2n+1'], match: [1, 3, 5]},
+  {args: ['2n+2'], match: [2, 4, 6]},
+  {args: ['-n+3'], match: [1, 2, 3]},
+  {args: ['2n', '3n'], match: [2, 3, 4, 6]},
+  {args: ['even'], match: [2, 4, 6]},
+  {args: ['odd'], match: [1, 3, 5]},
+];
+for (const el of els) {
+  const testName = el.outerHTML + (el.parentNode === document.body ? '' : ' in ' + el.parentNode.localName);
+
+  test(() => {
+    const matches = el.matches(':heading');
+    const shouldMatch = el.dataset.expectMatch !== "";
+    assert_equals(matches, shouldMatch);
+  }, testName + ' :heading');
+
+  for (const t of tests) {
+    const selector = `:heading(${t.args.join(', ')})`;
+    test(() => {
+      const matches = el.matches(selector);
+      const expectMatchLevel = parseInt(el.dataset.expectMatch, 10);
+      const shouldMatch = t.match.includes(expectMatchLevel);
+      assert_equals(matches, shouldMatch, selector);
+    }, testName + ' ' + selector);
+  }
+}
+</script>