diff --git a/public/html/single-file-example.html b/public/html/single-file-example.html
index 380a169f57b..65e800b11c8 100644
--- a/public/html/single-file-example.html
+++ b/public/html/single-file-example.html
@@ -1,4 +1,4 @@
-<!DOCTYPE html>
+<!doctype html>
 <html>
   <head>
     <meta charset="UTF-8" />
@@ -11,13 +11,9 @@
   </head>
   <body>
     <div id="root"></div>
+    <button>submit</button>
     <script type="text/babel">
-
-      ReactDOM.render(
-        <h1>Hello, world!</h1>,
-        document.getElementById('root')
-      );
-
+      ReactDOM.render(<h1>Hello, world!</h1>, document.getElementById('root'));
     </script>
     <!--
       Note: this page is a great way to try React but it's not suitable for production.
