diff --git a/css/css-backgrounds/background-attachment-fixed-block-002.html b/css/css-backgrounds/background-attachment-fixed-block-002.html
index 8b5c5e80427866..7936b027c6e5be 100644
--- a/css/css-backgrounds/background-attachment-fixed-block-002.html
+++ b/css/css-backgrounds/background-attachment-fixed-block-002.html
@@ -40,7 +40,14 @@
     }
   </style>
 
-  <body onload="window.scroll(0, document.body.offsetHeight); document.documentElement.classList.remove('reftest-wait');">
+  <script>
+
+  document.documentElement.addEventListener("TestRendered", () => {
+    window.scroll(0, document.body.offsetHeight);
+    document.documentElement.classList.remove('reftest-wait');
+  });
+
+  </script>
 
   <div>F</div>
 
diff --git a/css/css-backgrounds/background-attachment-fixed-inline-002.html b/css/css-backgrounds/background-attachment-fixed-inline-002.html
index b624a68060127c..9447b9d9b75c59 100644
--- a/css/css-backgrounds/background-attachment-fixed-inline-002.html
+++ b/css/css-backgrounds/background-attachment-fixed-inline-002.html
@@ -41,7 +41,14 @@
     }
   </style>
 
-  <body onload="window.scroll(0, document.body.offsetHeight); document.documentElement.classList.remove('reftest-wait');">
+  <script>
+
+  document.documentElement.addEventListener("TestRendered", () => {
+    window.scroll(0, document.body.offsetHeight);
+    document.documentElement.classList.remove('reftest-wait');
+  });
+
+  </script>
 
   <div>F</div>
 
diff --git a/css/css-backgrounds/background-attachment-local-block-002.html b/css/css-backgrounds/background-attachment-local-block-002.html
index ce19e360428eb3..edaabd175e98fd 100644
--- a/css/css-backgrounds/background-attachment-local-block-002.html
+++ b/css/css-backgrounds/background-attachment-local-block-002.html
@@ -40,7 +40,14 @@
     }
   </style>
 
-  <body onload="window.scroll(0, document.body.offsetHeight); document.documentElement.classList.remove('reftest-wait');">
+  <script>
+
+  document.documentElement.addEventListener("TestRendered", () => {
+    window.scroll(0, document.body.offsetHeight);
+    document.documentElement.classList.remove('reftest-wait');
+  });
+
+  </script>
 
   <div>F</div>
 
diff --git a/css/css-backgrounds/background-attachment-local-inline-002.html b/css/css-backgrounds/background-attachment-local-inline-002.html
index 8b877f9a14ccea..0ba846eebadaf2 100644
--- a/css/css-backgrounds/background-attachment-local-inline-002.html
+++ b/css/css-backgrounds/background-attachment-local-inline-002.html
@@ -41,7 +41,14 @@
     }
   </style>
 
-  <body onload="window.scroll(0, document.body.offsetHeight); document.documentElement.classList.remove('reftest-wait');">
+  <script>
+
+  document.documentElement.addEventListener("TestRendered", () => {
+    window.scroll(0, document.body.offsetHeight);
+    document.documentElement.classList.remove('reftest-wait');
+  });
+
+  </script>
 
   <div>F</div>
 
