Fix

src/core/hud.ts

         this.#fullscreenButton.init(parent, wantFullscreenButton);
         this.#supportWidget.init(parent);
 
+        for(const element of parent.children as any as HTMLElement[]) {
+            if(element.style.getPropertyValue('pointer-events') == '')
+                element.style.pointerEvents = 'auto'; // accept pointer input
+            if(element.style.getPropertyValue('z-index') == '')
+                element.style.zIndex = '1000000';
+        }
+
         const container = this._container;
         container.style.position = 'absolute';
         container.style.left = container.style.top = '0px';

src/ui/fullscreen-button.ts

         button.style.height = BUTTON_SIZE + 'px';
 
         button.style.opacity = '0.5';
-        button.style.zIndex = '1000000';
         button.style.cursor = 'pointer';
         button.style.outline = 'none';
         (button.style as any)['-webkit-tap-highlight-color'] = 'transparent';

src/ui/stats-panel.ts

 
         container.style.position = 'absolute';
         container.style.left = container.style.top = '0px';
-        container.style.zIndex = '1000000';
         container.style.padding = '0px';
 
         container.appendChild(this._createTitle());

src/ui/support-widget.ts

         button.style.transform = 'translateX(50%)';
 
         button.style.opacity = '0.75';
-        button.style.zIndex = '1000000';
         button.style.cursor = 'pointer';
         button.style.outline = 'none';
         (button.style as any)['-webkit-tap-highlight-color'] = 'transparent';