fix: strengthen status bar drop shadow and clarify positioning

Increase shadow spread (4px offset, 10px blur, 0.4 opacity) for a
more visible boundary between Android status bar and page content.

src/app.css

@@ -280,7 +280,9 @@ body {
 	overflow-x: hidden;
 }
 
-/* Status bar drop shadow for edge-to-edge Android/PWA */
+/* Status bar drop shadow for edge-to-edge Android/Tauri.
+   Sits flush at the top; the downward shadow marks the
+   boundary between status bar and page content. */
 body::before {
 	content: '';
 	position: fixed;
@@ -288,7 +290,7 @@ body::before {
 	left: 0;
 	right: 0;
 	height: env(safe-area-inset-top, 0px);
-	box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
+	box-shadow: 0 4px 10px rgba(0, 0, 0, 0.4);
 	z-index: 9999;
 	pointer-events: none;
 }