概要
This skill provides a comprehensive framework for writing clean, maintainable, and high-performance vanilla CSS without the need for preprocessors or utility frameworks. It enforces a strict 'Design Tokens First' approach using CSS variables for colors, typography, and spacing, while standardizing layout through a mobile-first philosophy. By utilizing BEM-inspired naming and native CSS Grid/Flexbox patterns, it helps developers build robust component-based interfaces that are accessible, themeable (with dark mode support), and easy to scale across large projects.