CSS rotation animation on #stirrer-blades group, speed mapped via --stir-duration custom property (speed=100 → 0.5s, speed=50 → 1s). Driven by stirrerSpeedIst on each Speed message. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DGKe8JzTM2Gr1fdx9wYXTi