Implement a CSS/JS Animation (Live UI Coding)

Requirements: Live-code a given UI animation (e.g., an element that fades/slides/scales in response to user interaction) from a shared spec or reference GIF, within the interview.

Design: Expect to be evaluated on: choosing the right tool for the animation (CSS transitions/keyframes for simple state-based animation vs the Web Animations API or a JS animation loop with requestAnimationFrame for more complex/interruptible sequences), structuring the component so animation state doesn't cause unnecessary re-renders (in a React context, keeping animation-driving state out of heavy re-render paths, or using CSS classes toggled via refs), and handling edge cases like animation interruption (user re-triggers the animation mid-flight) and accessibility (respecting prefers-reduced-motion).