Fix ViewTransition examples (#7999)

* Fix view transition example

* Empty commit

* Fix fullscreen example

src/content/reference/react/ViewTransition.md

@@ -159,7 +159,11 @@ Enter/Exit Transitions trigger when a `<ViewTransition>` is added or removed by
 
 ```js
 function Child() {
-  return <ViewTransition>Hi</ViewTransition>
+  return (
+    <ViewTransition>
+      <div>Hi</div>
+    </ViewTransition>
+  );
 }
 
 function Parent() {
@@ -352,11 +356,7 @@ button:hover {
 
 ```js [3, 5]
 function Component() {
-  return (
-    <div>
-      <ViewTransition>Hi</ViewTransition>
-    </div>
-  );
+  return <ViewTransition>Hi</ViewTransition>;
 }
 ```
 
@@ -519,7 +519,6 @@ button:hover {
   background-image: conic-gradient(at top right, #c76a15, #a6423a, #2b3491);
 }
 .thumbnail.fullscreen {
-  height: 100%;
   width: 100%;
 }
 .video {