--- a/layout/reftests/details-summary/details-in-ol-ref.html
+++ b/layout/reftests/details-summary/details-in-ol-ref.html
@@ -13,16 +13,24 @@
               <li>Second unordered item in summary</li>
             </ul>
             <div>
               <ol>
                 <li>First item in summary</li>
                 <li>Second item in summary</li>
               </ol>
             </div>
+            <svg>
+              <foreignObject width="300" height="300">
+                <ol>
+                  <li>First item in foreignObject</li>
+                  <li>Second item in foreignObject</li>
+                </ol>
+              </foreignObject>
+            </svg>
           </summary>
           <p>This is the details.</p>
           <li>First item in details</li>
           <li>Second item in details</li>
         </div>
       </li>
       <li>Second item</li>
     </ol>

--- a/layout/reftests/details-summary/details-in-ol.html
+++ b/layout/reftests/details-summary/details-in-ol.html
@@ -20,16 +20,24 @@
               <li>Second unordered item in summary</li>
             </ul>
             <div>
               <ol>
                 <li>First item in summary</li>
                 <li>Second item in summary</li>
               </ol>
             </div>
+            <svg>
+              <foreignObject width="300" height="300">
+                <ol>
+                  <li>First item in foreignObject</li>
+                  <li>Second item in foreignObject</li>
+                </ol>
+              </foreignObject>
+            </svg>
           </summary>
           <p>This is the details.</p>
           <!-- Although html spec does not allow <li> inside <details>, we
                deliberately omit the <ol> to test the renumbering isn't affected
                by the summary. -->
           <li>First item in details</li>
           <li>Second item in details</li>
         </details>

--- a/layout/style/res/html.css
+++ b/layout/style/res/html.css
@@ -779,17 +779,17 @@ video > .caption-box {
     list-style: disclosure-closed inside;
   }
 
   details[open] > summary:first-of-type,
   details[open] > summary:-moz-native-anonymous {
     list-style-type: disclosure-open;
   }
 
-  details > summary:first-of-type > * {
+  details > summary:first-of-type > *|* {
     /* Cancel "list-style-position: inside" inherited from summary. */
     list-style-position: initial;
   }
 }
 
 /* emulation of non-standard HTML <marquee> tag */
 marquee {
   inline-size: -moz-available;