diff --git a/testing/web-platform/tests/css/css-contain/content-visibility/content-visibility-035.html b/testing/web-platform/tests/css/css-contain/content-visibility/content-visibility-035.html
index e7f922a0d34bd..bc84c28d4a362 100644
--- a/testing/web-platform/tests/css/css-contain/content-visibility/content-visibility-035.html
+++ b/testing/web-platform/tests/css/css-contain/content-visibility/content-visibility-035.html
@@ -7,6 +7,8 @@
 <meta name="assert" content="content-visibility hidden element's subtree cannot be focused">
 <meta name="assert" content="content-visibility hidden element's subtree can access layout values">
 
+<body style="margin: 0">
+
 <div id="host">
   <input id="slotted" type="text">
 </div>
diff --git a/testing/web-platform/tests/css/css-contain/content-visibility/content-visibility-044.html b/testing/web-platform/tests/css/css-contain/content-visibility/content-visibility-044.html
index bf4f6168d414e..7378bcd71554a 100644
--- a/testing/web-platform/tests/css/css-contain/content-visibility/content-visibility-044.html
+++ b/testing/web-platform/tests/css/css-contain/content-visibility/content-visibility-044.html
@@ -9,6 +9,8 @@
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 
+<body style="margin: 0">
+
 <div id=host>
 <input id=slotted>
 <script>
