Understand how JavaScript execution blocks the main thread and affects animations
Only operates transform, continues when main thread is blocked.
Operates transform and width simultaneously, stops when main thread is blocked.
Completely depends on main thread, must stop.
Involves reflow, must stop.
The browser is like a factory. The **compositor thread** is a worker responsible for moving and rotating boxes; while the **main thread** is an engineer responsible for measuring sizes and manufacturing boxes.