What Is a Compositing Layer?
What is a compositing layer in CSS?
Answer out loud in under a minute: a definition, one concrete example, and one pitfall or trade-off.
Hints
Hint 1
Say what promotes an element to its own layer, what that buys for animation, and what it costs.
Solution
Show the approach
Answer
A part of the page painted into its own GPU texture. transform, opacity and will-change promote an element. The compositor can then move or fade it without layout or paint, which is why those two properties animate smoothly. Each layer costs memory, so promote sparingly.