Please improve the Pong game we just created. I am still a complete beginner.

Add arcade sound effects for paddle hits, wall bounces, points and winning, with a sound on/off button. Give the game more polished graphics and a clear start menu. Keep the existing Easy, Medium and Hard difficulty settings, with Easy selected by default, and keep Easy slow and forgiving.

Keep keyboard controls, the scoreboard, Start and Restart, and the rule that the first player to five points wins. Keep using HTML, CSS and JavaScript so I can open index.html directly in a browser without installing anything. Please test the changes and explain how I play the improved game.