Core Web Vitals
CLS (Cumulative Layout Shift)
Measures visual stability by tracking unexpected layout movements.
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What is CLS (Cumulative Layout Shift)
Cumulative Layout Shift (CLS) measures how much page content unexpectedly shifts during loading. High CLS frustrates users when elements move as they try to interact with the page.
Example
Good: <0.1, Needs Improvement: 0.1-0.25, Poor: >0.25. A button that moves as an ad loads above it = high CLS.
How to apply it
Set explicit dimensions for images/videos, reserve space for ads/embeds, avoid inserting content above existing content, use CSS transform for animations.
Tip:Ads are often the biggest CLS culprits. Reserve exact pixel dimensions for ad containers to prevent shifts when ads load.
Track it in GSC Boost
GSC Boost reads your Search Console data and tells you what to fix first, with the clicks each fix is likely to bring. Start with the guide or sign up free.
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