Added burger button for mobile - to hide the Quit/Menu (and future) UI buttons, giving more room for UI elements

index.html

@@ -16,8 +16,11 @@
 <body>
 
     <div id="ui" style="display: none;">
+        <button id="burgerButton" class="mobile-only">☰</button>
+        <div id="menuButtons">
         <button id="quitButton" class="button">Quit</button>
         <button id="uiButton" class="button">Menu</button>
+        </div>
     </div>    
     <div id="uiWidget" class="hidden">
         <div class="widget-tabs">