diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index f556de3c784..eaaf5ea3c94 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -7301,6 +7301,18 @@
      {}
     ]
    ],
+   "mozilla/partial_shadow_dom_layout_style.html": [
+    [
+     "mozilla/partial_shadow_dom_layout_style.html",
+     [
+      [
+       "/_mozilla/mozilla/partial_shadow_dom_layout_style_ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "mozilla/remove_link_styles.html": [
     [
      "mozilla/remove_link_styles.html",
@@ -10844,6 +10856,11 @@
      {}
     ]
    ],
+   "mozilla/partial_shadow_dom_layout_style_ref.html": [
+    [
+     {}
+    ]
+   ],
    "mozilla/poster.png": [
     [
      {}
@@ -20289,7 +20306,7 @@
    "testharness"
   ],
   "mozilla/interfaces.html": [
-   "a2b9fd23948319fabc0b5fff550b9565704b6678",
+   "c7e1929c626007e2ef3cdf9f2276620aa995c5b7",
    "testharness"
   ],
   "mozilla/interfaces.js": [
@@ -20440,6 +20457,14 @@
    "d97f1422d20161e989f200d44be6e379f79410bd",
    "testharness"
   ],
+  "mozilla/partial_shadow_dom_layout_style.html": [
+   "822e86bc07103351a5ceb2203fd9b6bee0c6367d",
+   "reftest"
+  ],
+  "mozilla/partial_shadow_dom_layout_style_ref.html": [
+   "bf40d2cc35b6b2c1e32afffa0651cb1b26e41fe8",
+   "support"
+  ],
   "mozilla/poster.png": [
    "33834c3ef095fa9c0080017e1b65b2eb8413eac4",
    "support"
diff --git a/tests/wpt/mozilla/meta/mozilla/partial_shadow_dom_layout_style.html.ini b/tests/wpt/mozilla/meta/mozilla/partial_shadow_dom_layout_style.html.ini
new file mode 100644
index 00000000000..6612e2fb467
--- /dev/null
+++ b/tests/wpt/mozilla/meta/mozilla/partial_shadow_dom_layout_style.html.ini
@@ -0,0 +1,2 @@
+[partial_shadow_dom_layout_style.html]
+  prefs: [dom.shadowdom.enabled:true]
diff --git a/tests/wpt/mozilla/tests/mozilla/partial_shadow_dom_layout_style.html b/tests/wpt/mozilla/tests/mozilla/partial_shadow_dom_layout_style.html
new file mode 100644
index 00000000000..822e86bc071
--- /dev/null
+++ b/tests/wpt/mozilla/tests/mozilla/partial_shadow_dom_layout_style.html
@@ -0,0 +1,22 @@
+<!doctype html>
+<html>
+  <meta charset="utf-8">
+  <title>Partial Shadow DOM support - layout & style</title>
+  <link rel="match" href="partial_shadow_dom_layout_style_ref.html">
+  <style>
+    h1 { color: red; }
+  </style>
+  <h1>Not in the shadows</h1>
+  <div id="host">
+  </div>
+  <script>
+    var host = document.getElementById('host');
+    var shadowRoot = host.attachShadow({ mode: 'closed' });
+    var shadowChild = document.createElement('h1');
+    shadowChild.textContent = 'In the shadows';
+    shadowRoot.appendChild(shadowChild);
+    var shadowStyles = document.createElement('style');
+    shadowStyles.textContent = 'h1 { color: blue; }';
+    shadowRoot.appendChild(shadowStyles);
+  </script>
+</html>
diff --git a/tests/wpt/mozilla/tests/mozilla/partial_shadow_dom_layout_style_ref.html b/tests/wpt/mozilla/tests/mozilla/partial_shadow_dom_layout_style_ref.html
new file mode 100644
index 00000000000..bf40d2cc35b
--- /dev/null
+++ b/tests/wpt/mozilla/tests/mozilla/partial_shadow_dom_layout_style_ref.html
@@ -0,0 +1,11 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>Partial Shadow DOM support - layout & style</title>
+<style>
+  h1 { color: red; }
+  .blue { color: blue; }
+</style>
+<h1>Not in the shadows</h1>
+<div id="host">
+  <h1 class='blue'>In the shadows</h1>
+</div>
