Enhance UI with mobile-friendly button styles

[afrigino]

Added styles for mobile touch targets and visual enhancements.

Summary of Changes:
Updated the index.css file to improve usability on touch devices and modernize the visual aesthetic.

Key Improvements:

• Accessibility: Increased minimum touch target size to 44px (easier to use on mobile/on deck).
• Visuals: Applied border-radius and drop-shadows for a modern "floating" aesthetic.
• Feedback: Added active states (Nautical Orange) to improve responsiveness.

No logic changes. Pure CSS overrides.