Instruction: Describe what CSS containment is and how it can be used to improve web performance.
Context: This question tests the candidate's knowledge on CSS containment property, a modern CSS feature aimed at allowing developers to isolate a subtree of the document to improve rendering performance.
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CSS containment, at its core, is a CSS property introduced to help developers improve the performance of their web pages by allowing them to isolate a subtree of the DOM. This is done through the contain property, which enables the browser to make assumptions about an element, optimizations that wouldn't be possible otherwise because the browser would have to consider how elements might affect the layout, style, paint, and size of the entire page.
The property can take several values such as layout, style, paint, and size – each serving a unique purpose:...