body { margin: 0; overflow: hidden; }
#ui { position: absolute; top: 10px; left: 10px; z-index: 10; }
button { font-size: 16px; margin: 2px; }
#mobile-controls { position: absolute; bottom: 10px; left: 50%; transform: translateX(-50%); z-index:10; }
#mobile-controls button { width: 60px; height: 60px; font-size: 18px; margin: 4px; }