Browser & Web Performance · Junior · Question 18 of 75

What does CLS (Cumulative Layout Shift) measure?

1How many CSS files block rendering
✓Correct answer: How much visible content unexpectedly moves around while the page is used
3How long layout calculations take

Explanation

CLS is a unitless score; a good value is 0.1 or less. Typical causes are images without dimensions, late ads and font swaps.

Further reading

web.dev: Cumulative Layout Shift ↗

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