Improve app responsiveness and visual consistency across devices

Adjusted layout, spacing, and element sizing in CalendarView, KanbanBoard, and ProjectTemplate components to enhance responsiveness and user experience on various screen sizes.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: ceced2fc-aa46-458d-ba87-ddd4b7bb1518
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/659922a9-0087-461c-90dd-6d9a58b81d4d/ceced2fc-aa46-458d-ba87-ddd4b7bb1518/gFHkSPu

client/src/App.tsx

@@ -316,7 +316,7 @@ function App() {
           </header>
 
           {/* Main Content */}
-          <main className="pb-20 px-4 py-6">
+          <main className="pb-20 px-3 py-4 sm:px-4 sm:py-6 max-w-screen-2xl mx-auto">
             {renderContent()}
           </main>