Set a fixed WASM screen size

Author: oskirby

wasm/test.html

@@ -15,7 +15,7 @@
     <style>
       /* Make the html body cover the entire (visual) viewport with no scroll bars. */
       html, body { padding: 0; margin: 0; overflow: hidden; height: 100% }
-      #screen { width: 100%; height: 100%; }
+      #screen { margin: auto; width: 360px; height: 640px; outline-style: solid; }
     </style>
     <link rel="icon" type="image/png" href="favicon.ico">
   </head>