Agent Skills: styling

StyleX styling system with project-specific design tokens, composable primitives, and custom css prop. MUST consult this skill before writing or modifying ANY styles in this project — the codebase uses custom design tokens, flex primitives, motion presets, and a css prop that differs from standard StyleX. Trigger whenever the user asks to create components, modify visual appearance, fix spacing/layout, add hover/focus effects, animations, responsive behavior, or anything involving CSS, styling, design tokens, breakpoints, or the css prop.