style changes especially sidebar

src/App.tsx

@@ -83,7 +83,7 @@ function App() {
             <Route path='/settings' element={<Settings />} />
           </Route>
 
-          <Route path="*" element={<h1 className="not-found">404<br/>Not Found</h1>} />
+          <Route path="*" element={<h1 className="not-found">404 [#]<br/>Not Found</h1>} />
         </Routes>
       </Router>
     </>