Enhance Game Styles and Visuals

We need to improve the visual aesthetics of the Snake game to make it more engaging and visually appealing. This includes updating the game's style elements such as backgrounds, fonts, and snake appearance.

## Tasks:

- Design and implement new background themes.
- Update snake and food sprites with improved graphics.
- Enhance the game’s font and text styles for better readability.
- Ensure all new styles are responsive and work across different screen sizes.

## Acceptance Criteria:

- The game should include at least three new background themes.
- The snake and food sprites should have a modern, polished look.
- Text elements should be clearly readable and visually consistent.
- Styles should be tested for responsiveness on different devices.