How to fix cwv cls on Klaviyo

Steps for Klaviyo

1. Email/SMS signup pop-ups and flyouts served by Klaviyo are a frequent source of CLS when they insert above or within page content. In your Klaviyo account, go to Sign-Up Forms.
2. For each active form, click Edit > select the Display Settings tab. Set 'Display Behavior' to a triggered/delayed display (e.g. 'Show after 5 seconds' or 'Show on exit intent') rather than 'Show immediately on page load' — this ensures the form does not inject before the page is fully painted.
3. For flyout/side-tab forms, confirm the form style is set to 'Flyout' or 'Full-Page' (overlay) not 'Embedded' — embedded forms inserted inline above product or blog content push surrounding elements down and cause significant CLS.
4. If you use an embedded inline form, wrap the Klaviyo embed code in a container div with a fixed min-height matching the form's pixel height, so the browser reserves the space even before the Klaviyo script fires.
5. Save and publish changes, then re-test your CLS on affected pages with Google PageSpeed Insights to confirm the shift caused by the form is eliminated.

What is cwv cls?

Cumulative Layout Shift (CLS) measures how much page content unexpectedly moves around while a visitor is looking at it. Every time an image pops in and shoves text down, a banner slides in from a cookie notice, or a font swap causes a paragraph to reflow, that counts as a layout shift. Google adds all those shifts together into a single score; anything above 0.1 is considered "needs improvement," and above 0.25 is "poor." A score of 1.35 (like the example above) means the page is shifting dramatically — visitors are misclicking, losing their place, and bouncing before they buy.

CLS is one of Google's three Core Web Vitals and is a direct ranking signal in Google Search — a poor score actively suppresses your position in search results, reducing organic traffic and revenue. On mobile, where most ecommerce shopping happens, layout shifts are especially jarring: a customer tapping "Add to Cart" can accidentally tap a shifted link instead, killing the conversion. High CLS also signals a low-quality page experience, which increases bounce rate and reduces the trust visitors place in your store. Google's own data shows that sites meeting Core Web Vitals thresholds see measurably better business outcomes than those that don't.

See the complete Cwv cls guide for every platform and the full background.