Cumulative Layout Shift scores unexpected movement of visible content. Good means 0.1 or less at p75. The main causes are images without dimensions, injected ads or banners, and web fonts changing metrics. Reserve space, preload fonts and never insert content above existing content.
The extended brief explains when this works, when it does not, and the trade-offs. Join the waitlist and it unlocks for every tip when sign-in opens; MCP access is the paid part.
Record a throttled load in the Performance panel and read the Layout Shifts track. Each entry names the node and the impacted region.
Check: The trace lists the shifting elements and their contribution to total CLS.
Reserve space and stabilise fonts
Add width and height or aspect-ratio to media, reserve container heights for embeds, and preload the above-the-fold font with a metric-compatible fallback.
Check: The trace shows zero layout shifts from images or fonts during load.
Confirm field improvement
Compare the Core Web Vitals report for the template across four-week windows after the fix ships.
Verify indexing with URL Inspection — URL Inspection shows the indexed version Google holds for one URL: crawl time, selected canonical, status code and blocked resources.
Canonicalize duplicate URLs — Duplicate URLs split signals across protocol, host, slash and parameter variants.
Make JavaScript content crawlable — Google renders JavaScript, but rendering costs time and AI retrieval systems often read raw HTML.