css

Expert-level CSS development with modern features and best practices. Use when asked to (1) write or debug CSS, (2) implement layouts with flexbox, grid, or container queries, (3) create animations and transitions, (4) optimize CSS performance, (5) work with CSS preprocessors or CSS-in-JS, (6) implement responsive design, or when phrases like "style", "CSS", "stylesheet", "design", "layout", "animation" appear.