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Layout shifts

Silktide watches your page as it loads and measures how much the layout jumps around, identifying the specific parts of the page that move. A stable page appears once and stays put; an unstable one shifts as images, fonts, and embeds arrive.

The measurement is Cumulative Layout Shift (CLS), one of Google's . It adds up every unexpected movement during loading: 0.1 or less is considered good, and 0.25 or more is considered poor.

Why this matters

Layout shifts cause real mistakes. A visitor goes to tap a link, the content jumps at the last moment, and they tap something else - sometimes an ad, sometimes "Buy" instead of "Cancel". Text the visitor is reading leaps out from under them. It makes a site feel broken and untrustworthy in a way visitors notice immediately even if they can't name it.

Google also uses Core Web Vitals, including this one, as a search ranking signal, so an unstable page can cost visibility as well as goodwill.

How to fix it

Silktide shows which elements shifted; the fix is to reserve their space before they load.

  1. Give every image and video an explicit width and height (or a CSS aspect ratio), so the browser reserves the right space before the file arrives - see Explicit image sizes.
  2. Reserve space for ads, embeds, and other late-loading content with a fixed-size container, even if it is sometimes partly empty.
  3. Never insert new content above what the visitor is already reading, unless it is in response to their own action.
  4. Load custom fonts in a way that avoids visible reflowing of text - see Visible loading text.

How Silktide tests this

  1. Load the page in a real browser, using the device type, connection speed, and test location configured for your speed tests.
  2. Record every unexpected layout movement while the page loads, and total them into the page's Cumulative Layout Shift score.
  3. Report each element that shifted, with its and its individual contribution to the total.
  4. Grade the page by its total score, on the public scale for this measurement: 0.1 or less is good, 0.25 or more is poor.

Troubleshooting

I don't see the page move

Shifts often happen in the first moments of loading, before you start reading, or only on slower connections where files arrive spread out over time. Your browser may also have the page's images and fonts cached, so nothing needs to arrive late. The elements listed by the check pinpoint what moved, however briefly.

My score differs from other tools

CLS depends on device, connection speed, and how far the measurement extends. Silktide measures a controlled page load with your configured speed test settings; tools based on real visitor data (or that keep measuring while users scroll and interact) can legitimately report different values for the same page.

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Layout shifts | Silktide Help