diff --git a/tests/ref/400x400_green.png b/tests/ref/400x400_green.png
deleted file mode 100644
index 484469eb140..00000000000
Binary files a/tests/ref/400x400_green.png and /dev/null differ
diff --git a/tests/ref/4x2.png b/tests/ref/4x2.png
deleted file mode 100644
index eb0c5cda971..00000000000
Binary files a/tests/ref/4x2.png and /dev/null differ
diff --git a/tests/ref/basic.list b/tests/ref/basic.list
index 7e8551c33e3..ead25bc53d7 100644
--- a/tests/ref/basic.list
+++ b/tests/ref/basic.list
@@ -11,11 +11,6 @@ fragment=top != ../html/acid2.html acid2_ref.html
 
 == acid2_noscroll.html acid2_ref_broken.html
 flaky_cpu == append_style_a.html append_style_b.html
-== fixed_width_overrides_child_intrinsic_width_a.html fixed_width_overrides_child_intrinsic_width_ref.html
-prefs:"layout.flex-direction.enabled,layout.flex.enabled" == flex_column_direction.html flex_column_direction_ref.html
-prefs:"layout.flex.enabled" == flex_row_direction.html flex_row_direction_ref.html
-== floated_negative_margins_a.html floated_negative_margins_ref.html
-== font_size.html font_size_ref.html
 # `?` and `#` in the name is a test for https://github.com/servo/servo/issues/3340
 
 == iframe/bg_color.html iframe/bg_color_ref.html
@@ -39,11 +34,6 @@ prefs:"layout.writing-mode.enabled" == iframe/size_attributes_vertical_writing_m
 == iframe/stacking_context.html iframe/stacking_context_ref.html
 == iframe/stacking_context_position_a.html iframe/stacking_context_position_ref.html
 
-!= image_rendering_auto_a.html image_rendering_pixelated_a.html
-== image_rendering_pixelated_a.html image_rendering_pixelated_ref.html
-== img_block_maxwidth_a.html img_block_maxwidth_ref.html
-== img_block_maxwidth_b.html img_block_maxwidth_ref.html
-!= img_simple.html img_simple_ref.html
 != inline_background_a.html inline_background_ref.html
 == inline_block_margin_auto_a.html inline_block_margin_auto_ref.html
 == inline_block_parent_width.html inline_block_parent_width_ref.html
diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index 2e3125883ab..340cbde980b 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -1259,6 +1259,30 @@
             "url": "/_mozilla/css/first_of_type_pseudo_a.html"
           }
         ],
+        "css/fixed_width_overrides_child_intrinsic_width_a.html": [
+          {
+            "path": "css/fixed_width_overrides_child_intrinsic_width_a.html",
+            "references": [
+              [
+                "/_mozilla/css/fixed_width_overrides_child_intrinsic_width_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/fixed_width_overrides_child_intrinsic_width_a.html"
+          }
+        ],
+        "css/flex_column_direction.html": [
+          {
+            "path": "css/flex_column_direction.html",
+            "references": [
+              [
+                "/_mozilla/css/flex_column_direction_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/flex_column_direction.html"
+          }
+        ],
         "css/flex_nochild.html": [
           {
             "path": "css/flex_nochild.html",
@@ -1271,6 +1295,18 @@
             "url": "/_mozilla/css/flex_nochild.html"
           }
         ],
+        "css/flex_row_direction.html": [
+          {
+            "path": "css/flex_row_direction.html",
+            "references": [
+              [
+                "/_mozilla/css/flex_row_direction_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/flex_row_direction.html"
+          }
+        ],
         "css/float_clearance_a.html": [
           {
             "path": "css/float_clearance_a.html",
@@ -1403,6 +1439,18 @@
             "url": "/_mozilla/css/floated_list_item_a.html"
           }
         ],
+        "css/floated_negative_margins_a.html": [
+          {
+            "path": "css/floated_negative_margins_a.html",
+            "references": [
+              [
+                "/_mozilla/css/floated_negative_margins_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/floated_negative_margins_a.html"
+          }
+        ],
         "css/floated_table_with_margin_a.html": [
           {
             "path": "css/floated_table_with_margin_a.html",
@@ -1463,6 +1511,18 @@
             "url": "/_mozilla/css/font_face_attribute.html"
           }
         ],
+        "css/font_size.html": [
+          {
+            "path": "css/font_size.html",
+            "references": [
+              [
+                "/_mozilla/css/font_size_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/font_size.html"
+          }
+        ],
         "css/font_style.html": [
           {
             "path": "css/font_style.html",
@@ -1499,6 +1559,30 @@
             "url": "/_mozilla/css/hide_after_create.html"
           }
         ],
+        "css/image_rendering_auto_a.html": [
+          {
+            "path": "css/image_rendering_auto_a.html",
+            "references": [
+              [
+                "/_mozilla/css/image_rendering_pixelated_a.html",
+                "!="
+              ]
+            ],
+            "url": "/_mozilla/css/image_rendering_auto_a.html"
+          }
+        ],
+        "css/image_rendering_pixelated_a.html": [
+          {
+            "path": "css/image_rendering_pixelated_a.html",
+            "references": [
+              [
+                "/_mozilla/css/image_rendering_pixelated_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/image_rendering_pixelated_a.html"
+          }
+        ],
         "css/img_block_display_a.html": [
           {
             "path": "css/img_block_display_a.html",
@@ -1511,6 +1595,30 @@
             "url": "/_mozilla/css/img_block_display_a.html"
           }
         ],
+        "css/img_block_maxwidth_a.html": [
+          {
+            "path": "css/img_block_maxwidth_a.html",
+            "references": [
+              [
+                "/_mozilla/css/img_block_maxwidth_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/img_block_maxwidth_a.html"
+          }
+        ],
+        "css/img_block_maxwidth_b.html": [
+          {
+            "path": "css/img_block_maxwidth_b.html",
+            "references": [
+              [
+                "/_mozilla/css/img_block_maxwidth_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/img_block_maxwidth_b.html"
+          }
+        ],
         "css/img_dynamic_remove.html": [
           {
             "path": "css/img_dynamic_remove.html",
@@ -1535,6 +1643,18 @@
             "url": "/_mozilla/css/img_padding_a.html"
           }
         ],
+        "css/img_simple.html": [
+          {
+            "path": "css/img_simple.html",
+            "references": [
+              [
+                "/_mozilla/css/img_simple_ref.html",
+                "!="
+              ]
+            ],
+            "url": "/_mozilla/css/img_simple.html"
+          }
+        ],
         "css/img_size_a.html": [
           {
             "path": "css/img_size_a.html",
@@ -6072,6 +6192,30 @@
           "url": "/_mozilla/css/first_of_type_pseudo_a.html"
         }
       ],
+      "css/fixed_width_overrides_child_intrinsic_width_a.html": [
+        {
+          "path": "css/fixed_width_overrides_child_intrinsic_width_a.html",
+          "references": [
+            [
+              "/_mozilla/css/fixed_width_overrides_child_intrinsic_width_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/fixed_width_overrides_child_intrinsic_width_a.html"
+        }
+      ],
+      "css/flex_column_direction.html": [
+        {
+          "path": "css/flex_column_direction.html",
+          "references": [
+            [
+              "/_mozilla/css/flex_column_direction_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/flex_column_direction.html"
+        }
+      ],
       "css/flex_nochild.html": [
         {
           "path": "css/flex_nochild.html",
@@ -6084,6 +6228,18 @@
           "url": "/_mozilla/css/flex_nochild.html"
         }
       ],
+      "css/flex_row_direction.html": [
+        {
+          "path": "css/flex_row_direction.html",
+          "references": [
+            [
+              "/_mozilla/css/flex_row_direction_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/flex_row_direction.html"
+        }
+      ],
       "css/float_clearance_a.html": [
         {
           "path": "css/float_clearance_a.html",
@@ -6216,6 +6372,18 @@
           "url": "/_mozilla/css/floated_list_item_a.html"
         }
       ],
+      "css/floated_negative_margins_a.html": [
+        {
+          "path": "css/floated_negative_margins_a.html",
+          "references": [
+            [
+              "/_mozilla/css/floated_negative_margins_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/floated_negative_margins_a.html"
+        }
+      ],
       "css/floated_table_with_margin_a.html": [
         {
           "path": "css/floated_table_with_margin_a.html",
@@ -6276,6 +6444,18 @@
           "url": "/_mozilla/css/font_face_attribute.html"
         }
       ],
+      "css/font_size.html": [
+        {
+          "path": "css/font_size.html",
+          "references": [
+            [
+              "/_mozilla/css/font_size_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/font_size.html"
+        }
+      ],
       "css/font_style.html": [
         {
           "path": "css/font_style.html",
@@ -6312,6 +6492,30 @@
           "url": "/_mozilla/css/hide_after_create.html"
         }
       ],
+      "css/image_rendering_auto_a.html": [
+        {
+          "path": "css/image_rendering_auto_a.html",
+          "references": [
+            [
+              "/_mozilla/css/image_rendering_pixelated_a.html",
+              "!="
+            ]
+          ],
+          "url": "/_mozilla/css/image_rendering_auto_a.html"
+        }
+      ],
+      "css/image_rendering_pixelated_a.html": [
+        {
+          "path": "css/image_rendering_pixelated_a.html",
+          "references": [
+            [
+              "/_mozilla/css/image_rendering_pixelated_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/image_rendering_pixelated_a.html"
+        }
+      ],
       "css/img_block_display_a.html": [
         {
           "path": "css/img_block_display_a.html",
@@ -6324,6 +6528,30 @@
           "url": "/_mozilla/css/img_block_display_a.html"
         }
       ],
+      "css/img_block_maxwidth_a.html": [
+        {
+          "path": "css/img_block_maxwidth_a.html",
+          "references": [
+            [
+              "/_mozilla/css/img_block_maxwidth_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/img_block_maxwidth_a.html"
+        }
+      ],
+      "css/img_block_maxwidth_b.html": [
+        {
+          "path": "css/img_block_maxwidth_b.html",
+          "references": [
+            [
+              "/_mozilla/css/img_block_maxwidth_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/img_block_maxwidth_b.html"
+        }
+      ],
       "css/img_dynamic_remove.html": [
         {
           "path": "css/img_dynamic_remove.html",
@@ -6348,6 +6576,18 @@
           "url": "/_mozilla/css/img_padding_a.html"
         }
       ],
+      "css/img_simple.html": [
+        {
+          "path": "css/img_simple.html",
+          "references": [
+            [
+              "/_mozilla/css/img_simple_ref.html",
+              "!="
+            ]
+          ],
+          "url": "/_mozilla/css/img_simple.html"
+        }
+      ],
       "css/img_size_a.html": [
         {
           "path": "css/img_size_a.html",
diff --git a/tests/ref/fixed_width_overrides_child_intrinsic_width_a.html b/tests/wpt/mozilla/tests/css/fixed_width_overrides_child_intrinsic_width_a.html
similarity index 88%
rename from tests/ref/fixed_width_overrides_child_intrinsic_width_a.html
rename to tests/wpt/mozilla/tests/css/fixed_width_overrides_child_intrinsic_width_a.html
index 33e9e7c629b..f12c3e9e65a 100644
--- a/tests/ref/fixed_width_overrides_child_intrinsic_width_a.html
+++ b/tests/wpt/mozilla/tests/css/fixed_width_overrides_child_intrinsic_width_a.html
@@ -1,6 +1,7 @@
 <!DOCTYPE html>
 <html>
     <head>
+        <link rel=match href=fixed_width_overrides_child_intrinsic_width_ref.html>
         <style type="text/css">
             body {
                 font-family: 'ahem';
diff --git a/tests/ref/fixed_width_overrides_child_intrinsic_width_ref.html b/tests/wpt/mozilla/tests/css/fixed_width_overrides_child_intrinsic_width_ref.html
similarity index 100%
rename from tests/ref/fixed_width_overrides_child_intrinsic_width_ref.html
rename to tests/wpt/mozilla/tests/css/fixed_width_overrides_child_intrinsic_width_ref.html
diff --git a/tests/ref/flex_column_direction.html b/tests/wpt/mozilla/tests/css/flex_column_direction.html
similarity index 93%
rename from tests/ref/flex_column_direction.html
rename to tests/wpt/mozilla/tests/css/flex_column_direction.html
index c63bc6b1ee7..a4c612feff9 100644
--- a/tests/ref/flex_column_direction.html
+++ b/tests/wpt/mozilla/tests/css/flex_column_direction.html
@@ -5,6 +5,7 @@
   <title>CSS Test: flex container should layout flex items horizontally</title>
   <link rel="author" title="Kyle Zentner" href="mailto:zentner.kyle@gmail.com">
   <link rel="help" href="https://drafts.csswg.org/css-flexbox/">
+  <link rel=match href=flex_column_direction_ref.html>
   <style>
     body {
       margin: 0;
diff --git a/tests/ref/flex_column_direction_ref.html b/tests/wpt/mozilla/tests/css/flex_column_direction_ref.html
similarity index 100%
rename from tests/ref/flex_column_direction_ref.html
rename to tests/wpt/mozilla/tests/css/flex_column_direction_ref.html
diff --git a/tests/ref/flex_row_direction.html b/tests/wpt/mozilla/tests/css/flex_row_direction.html
similarity index 93%
rename from tests/ref/flex_row_direction.html
rename to tests/wpt/mozilla/tests/css/flex_row_direction.html
index 68689e5eca9..b2ec3650905 100644
--- a/tests/ref/flex_row_direction.html
+++ b/tests/wpt/mozilla/tests/css/flex_row_direction.html
@@ -5,6 +5,7 @@
   <title>CSS Test: flex container should layout flex items horizontally</title>
   <link rel="author" title="Kyle Zentner" href="mailto:zentner.kyle@gmail.com">
   <link rel="help" href="https://drafts.csswg.org/css-flexbox/">
+  <link rel=match href=flex_row_direction_ref.html>
   <style>
     body {
       margin: 0;
diff --git a/tests/ref/flex_row_direction_ref.html b/tests/wpt/mozilla/tests/css/flex_row_direction_ref.html
similarity index 100%
rename from tests/ref/flex_row_direction_ref.html
rename to tests/wpt/mozilla/tests/css/flex_row_direction_ref.html
diff --git a/tests/ref/floated_negative_margins_a.html b/tests/wpt/mozilla/tests/css/floated_negative_margins_a.html
similarity index 77%
rename from tests/ref/floated_negative_margins_a.html
rename to tests/wpt/mozilla/tests/css/floated_negative_margins_a.html
index 49e3e9b5d6b..62b2859b2b3 100644
--- a/tests/ref/floated_negative_margins_a.html
+++ b/tests/wpt/mozilla/tests/css/floated_negative_margins_a.html
@@ -1,3 +1,4 @@
+<link rel=match href=floated_negative_margins_ref.html>
 <style>
 body {
     margin: 0;
diff --git a/tests/ref/floated_negative_margins_ref.html b/tests/wpt/mozilla/tests/css/floated_negative_margins_ref.html
similarity index 100%
rename from tests/ref/floated_negative_margins_ref.html
rename to tests/wpt/mozilla/tests/css/floated_negative_margins_ref.html
diff --git a/tests/ref/font_size.html b/tests/wpt/mozilla/tests/css/font_size.html
similarity index 94%
rename from tests/ref/font_size.html
rename to tests/wpt/mozilla/tests/css/font_size.html
index 7c500513bcb..04b7ef1a0c7 100644
--- a/tests/ref/font_size.html
+++ b/tests/wpt/mozilla/tests/css/font_size.html
@@ -1,5 +1,6 @@
 <!DOCTYPE html>
 <title>font-size (issues #1435, #3417)</title>
+<link rel=match href=font_size_ref.html>
 <style>p { margin: .5em }</style>
 <body style="font-size: 20px">
 <p style="font-size: 24pt">24pt is 32px.
diff --git a/tests/ref/font_size_ref.html b/tests/wpt/mozilla/tests/css/font_size_ref.html
similarity index 100%
rename from tests/ref/font_size_ref.html
rename to tests/wpt/mozilla/tests/css/font_size_ref.html
diff --git a/tests/ref/image_rendering_auto_a.html b/tests/wpt/mozilla/tests/css/image_rendering_auto_a.html
similarity index 80%
rename from tests/ref/image_rendering_auto_a.html
rename to tests/wpt/mozilla/tests/css/image_rendering_auto_a.html
index 440bfa9abd8..37f65265af7 100644
--- a/tests/ref/image_rendering_auto_a.html
+++ b/tests/wpt/mozilla/tests/css/image_rendering_auto_a.html
@@ -2,6 +2,7 @@
 <html>
 <head>
 <!-- Tests that `image-rendering: auto` uses bilinear filtering. -->
+<link rel=mismatch href=image_rendering_pixelated_a.html>
 <style>
 img {
     position: absolute;
diff --git a/tests/ref/image_rendering_pixelated_a.html b/tests/wpt/mozilla/tests/css/image_rendering_pixelated_a.html
similarity index 86%
rename from tests/ref/image_rendering_pixelated_a.html
rename to tests/wpt/mozilla/tests/css/image_rendering_pixelated_a.html
index b4086e2fd33..81774f7ebcf 100644
--- a/tests/ref/image_rendering_pixelated_a.html
+++ b/tests/wpt/mozilla/tests/css/image_rendering_pixelated_a.html
@@ -2,6 +2,7 @@
 <html>
 <head>
 <!-- Tests that `image-rendering: pixelated` causes nearest-neighbor interpolation to be used. -->
+<link rel=match href=image_rendering_pixelated_ref.html>
 <style>
 img {
     position: absolute;
diff --git a/tests/ref/image_rendering_pixelated_ref.html b/tests/wpt/mozilla/tests/css/image_rendering_pixelated_ref.html
similarity index 100%
rename from tests/ref/image_rendering_pixelated_ref.html
rename to tests/wpt/mozilla/tests/css/image_rendering_pixelated_ref.html
diff --git a/tests/ref/img_block_maxwidth_a.html b/tests/wpt/mozilla/tests/css/img_block_maxwidth_a.html
similarity index 84%
rename from tests/ref/img_block_maxwidth_a.html
rename to tests/wpt/mozilla/tests/css/img_block_maxwidth_a.html
index a36f5c9001d..b4978341652 100644
--- a/tests/ref/img_block_maxwidth_a.html
+++ b/tests/wpt/mozilla/tests/css/img_block_maxwidth_a.html
@@ -1,6 +1,7 @@
 <!DOCTYPE html>
 <html>
     <head>
+        <link rel=match href=img_block_maxwidth_ref.html>
         <style type="text/css">
             body {
                 margin: 0;
diff --git a/tests/ref/img_block_maxwidth_b.html b/tests/wpt/mozilla/tests/css/img_block_maxwidth_b.html
similarity index 83%
rename from tests/ref/img_block_maxwidth_b.html
rename to tests/wpt/mozilla/tests/css/img_block_maxwidth_b.html
index 315a36602e1..6a3cf1a15b1 100644
--- a/tests/ref/img_block_maxwidth_b.html
+++ b/tests/wpt/mozilla/tests/css/img_block_maxwidth_b.html
@@ -1,6 +1,7 @@
 <!DOCTYPE html>
 <html>
     <head>
+        <link rel=match href=img_block_maxwidth_ref.html>
         <style type="text/css">
             body {
                 margin: 0;
diff --git a/tests/ref/img_block_maxwidth_ref.html b/tests/wpt/mozilla/tests/css/img_block_maxwidth_ref.html
similarity index 100%
rename from tests/ref/img_block_maxwidth_ref.html
rename to tests/wpt/mozilla/tests/css/img_block_maxwidth_ref.html
diff --git a/tests/ref/img_simple.html b/tests/wpt/mozilla/tests/css/img_simple.html
similarity index 52%
rename from tests/ref/img_simple.html
rename to tests/wpt/mozilla/tests/css/img_simple.html
index 056cef562c9..792efb30cc4 100644
--- a/tests/ref/img_simple.html
+++ b/tests/wpt/mozilla/tests/css/img_simple.html
@@ -1,3 +1,4 @@
 <!doctype html>
+<link rel=mismatch href=img_simple_ref.html>
 Hello
 <img src=400x400_green.png>
diff --git a/tests/ref/img_simple_ref.html b/tests/wpt/mozilla/tests/css/img_simple_ref.html
similarity index 100%
rename from tests/ref/img_simple_ref.html
rename to tests/wpt/mozilla/tests/css/img_simple_ref.html