diff --git a/tests/ref/basic.list b/tests/ref/basic.list
index 6b516b9cba5..60c869a4d84 100644
--- a/tests/ref/basic.list
+++ b/tests/ref/basic.list
@@ -6,8 +6,6 @@ fragment=top != ../html/acid2.html acid2_ref.html
 
 resolution=300x300,device-pixel-ratio=2 != pixel_snapping_border_a.html pixel_snapping_border_ref.html
 resolution=300x300,device-pixel-ratio=2 != pixel_snapping_position_a.html pixel_snapping_position_ref.html
-resolution=800x600 == viewport_percentage_vw_vh.html viewport_percentage_vw_vh_a.html
-# resolution=600x800 == viewport_percentage_vw_vh.html viewport_percentage_vw_vh_b.html
 
 # This file must be sorted alphabetically.
 # Please run `./mach test-tidy` to check your changes.
diff --git a/tests/wpt/css-tests/tools/manifest/item.py b/tests/wpt/css-tests/tools/manifest/item.py
index 702682cd70e..8ee17004495 100644
--- a/tests/wpt/css-tests/tools/manifest/item.py
+++ b/tests/wpt/css-tests/tools/manifest/item.py
@@ -123,26 +123,29 @@ class RefTest(URLManifestItem):
     item_type = "reftest"
 
     def __init__(self, source_file, url, references, url_base="/", timeout=None,
-                 manifest=None):
+                 viewport_size=None, manifest=None):
         URLManifestItem.__init__(self, source_file, url, url_base=url_base, manifest=manifest)
         for _, ref_type in references:
             if ref_type not in ["==", "!="]:
                 raise ValueError, "Unrecognised ref_type %s" % ref_type
         self.references = tuple(references)
         self.timeout = timeout
+        self.viewport_size = viewport_size
 
     @property
     def is_reference(self):
         return self.source_file.name_is_reference
 
     def meta_key(self):
-        return (self.timeout,)
+        return (self.timeout, self.viewport_size)
 
     def to_json(self):
         rv = URLManifestItem.to_json(self)
         rv["references"] = self.references
         if self.timeout is not None:
             rv["timeout"] = self.timeout
+        if self.viewport_size is not None:
+            rv["viewport_size"] = self.viewport_size
         return rv
 
     @classmethod
@@ -153,6 +156,7 @@ class RefTest(URLManifestItem):
                    obj["references"],
                    url_base=manifest.url_base,
                    timeout=obj.get("timeout"),
+                   viewport_size=obj.get("viewport_size"),
                    manifest=manifest)
 
 
diff --git a/tests/wpt/css-tests/tools/manifest/sourcefile.py b/tests/wpt/css-tests/tools/manifest/sourcefile.py
index 7c0f976a44b..3681f85276e 100644
--- a/tests/wpt/css-tests/tools/manifest/sourcefile.py
+++ b/tests/wpt/css-tests/tools/manifest/sourcefile.py
@@ -180,6 +180,23 @@ class SourceFile(object):
             if timeout_str and timeout_str.lower() == "long":
                 return timeout_str
 
+    @cached_property
+    def viewport_nodes(self):
+        """List of ElementTree Elements corresponding to nodes in a test that
+        specify viewport sizes"""
+        return self.root.findall(".//{http://www.w3.org/1999/xhtml}meta[@name='viewport-size']")
+
+    @cached_property
+    def viewport_size(self):
+        """The viewport size of a test or reference file"""
+        if not self.root:
+            return None
+
+        if not self.viewport_nodes:
+            return None
+
+        return self.viewport_nodes[0].attrib.get("content", None)
+
     @cached_property
     def testharness_nodes(self):
         """List of ElementTree Elements corresponding to nodes representing a
@@ -271,7 +288,7 @@ class SourceFile(object):
                 rv.append(TestharnessTest(self, url, timeout=self.timeout))
 
         elif self.content_is_ref_node:
-            rv = [RefTest(self, self.url, self.references, timeout=self.timeout)]
+            rv = [RefTest(self, self.url, self.references, timeout=self.timeout, viewport_size=self.viewport_size)]
 
         else:
             # If nothing else it's a helper file, which we don't have a specific type for
diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index 745b7c191ba..88add1dbdf1 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -4893,6 +4893,32 @@
             "viewport_size": "500x700"
           }
         ],
+        "css/viewport_percentage_vw_vh_a.html": [
+          {
+            "path": "css/viewport_percentage_vw_vh_a.html",
+            "references": [
+              [
+                "/_mozilla/css/viewport_percentage_vw_vh_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/viewport_percentage_vw_vh_a.html",
+            "viewport_size": "700x500"
+          }
+        ],
+        "css/viewport_percentage_vw_vh_b.html": [
+          {
+            "path": "css/viewport_percentage_vw_vh_b.html",
+            "references": [
+              [
+                "/_mozilla/css/viewport_percentage_vw_vh_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/viewport_percentage_vw_vh_b.html",
+            "viewport_size": "500x700"
+          }
+        ],
         "css/viewport_rule.html": [
           {
             "path": "css/viewport_rule.html",
@@ -10852,6 +10878,32 @@
           "viewport_size": "500x700"
         }
       ],
+      "css/viewport_percentage_vw_vh_a.html": [
+        {
+          "path": "css/viewport_percentage_vw_vh_a.html",
+          "references": [
+            [
+              "/_mozilla/css/viewport_percentage_vw_vh_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/viewport_percentage_vw_vh_a.html",
+          "viewport_size": "700x500"
+        }
+      ],
+      "css/viewport_percentage_vw_vh_b.html": [
+        {
+          "path": "css/viewport_percentage_vw_vh_b.html",
+          "references": [
+            [
+              "/_mozilla/css/viewport_percentage_vw_vh_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/viewport_percentage_vw_vh_b.html",
+          "viewport_size": "500x700"
+        }
+      ],
       "css/viewport_rule.html": [
         {
           "path": "css/viewport_rule.html",
diff --git a/tests/ref/viewport_percentage_vw_vh_a.html b/tests/wpt/mozilla/tests/css/viewport_percentage_vw_vh_a.html
similarity index 53%
rename from tests/ref/viewport_percentage_vw_vh_a.html
rename to tests/wpt/mozilla/tests/css/viewport_percentage_vw_vh_a.html
index 116b3a05481..4ae0d07e923 100644
--- a/tests/ref/viewport_percentage_vw_vh_a.html
+++ b/tests/wpt/mozilla/tests/css/viewport_percentage_vw_vh_a.html
@@ -1,11 +1,13 @@
 <!DOCTYPE html>
 <html>
   <head>
+    <meta name=viewport-size content=700x500>
+    <link rel=match href=viewport_percentage_vw_vh_ref.html>
     <style>
       #box {
         background: green;
-        height: 300px;
-        width: 400px;
+        height: 42vh;
+        width: 50vw;
       }
     </style>
   </head>
diff --git a/tests/ref/viewport_percentage_vw_vh_b.html b/tests/wpt/mozilla/tests/css/viewport_percentage_vw_vh_b.html
similarity index 53%
rename from tests/ref/viewport_percentage_vw_vh_b.html
rename to tests/wpt/mozilla/tests/css/viewport_percentage_vw_vh_b.html
index d67f728bc8f..6d306b5ff82 100644
--- a/tests/ref/viewport_percentage_vw_vh_b.html
+++ b/tests/wpt/mozilla/tests/css/viewport_percentage_vw_vh_b.html
@@ -1,11 +1,13 @@
 <!DOCTYPE html>
 <html>
   <head>
+    <meta name=viewport-size content=500x700>
+    <link rel=match href=viewport_percentage_vw_vh_ref.html>
     <style>
       #box {
         background: green;
-        height: 400px;
-        width: 300px;
+        height: 30vh;
+        width: 70vw;
       }
     </style>
   </head>
diff --git a/tests/ref/viewport_percentage_vw_vh.html b/tests/wpt/mozilla/tests/css/viewport_percentage_vw_vh_ref.html
similarity index 79%
rename from tests/ref/viewport_percentage_vw_vh.html
rename to tests/wpt/mozilla/tests/css/viewport_percentage_vw_vh_ref.html
index 11e6f5b00bf..07146c46a08 100644
--- a/tests/ref/viewport_percentage_vw_vh.html
+++ b/tests/wpt/mozilla/tests/css/viewport_percentage_vw_vh_ref.html
@@ -4,8 +4,8 @@
     <style>
       #box {
         background: green;
-        height: 50vh;
-        width: 50vw;
+        height: 210px;
+        width: 350px;
       }
     </style>
   </head>