Update Colored Sidebar Items.css

[seb3point0]

refactor: optimize and simplify CSS for colored sidebar items

• Consolidated common styles for folder titles, hover states, and file titles into shared rules to reduce repetition.
• Utilized CSS custom properties to dynamically apply colors based on folder prefixes.
• Reduced redundant code by applying common indentation and hover effects globally.
• Improved maintainability by centralizing color definitions and simplifying folder-specific rules.