Refactor CSS formatting for improved readability

[namingbe]

Summary

This PR reformats the CSS stylesheet in playground.html to improve code readability and maintainability by expanding multi-property declarations across multiple lines.

Key Changes

• Expanded all CSS rule declarations from single-line to multi-line format for better readability
• Each CSS property is now on its own line with consistent indentation
• Added blank lines between related CSS rule groups for visual separation
• No functional changes to the styling—this is purely a formatting improvement

Implementation Details

• All selectors and their property declarations maintain the same specificity and cascade behavior
• The reformatting follows a consistent pattern: opening brace on the same line as the selector, each property on its own line, closing brace on its own line
• Blank lines are strategically placed between logical groups of rules (e.g., between .btn and .btn:hover, between different component sections)
• This change makes the CSS easier to review, maintain, and reduces merge conflicts when multiple developers modify different properties within the same rule

https://claude.ai/code/session_01S3ETpFXfDZUnDPky8Vs6Gw