How to fix cwv cls on Squarespace

Steps for Squarespace

1. Images: Squarespace automatically outputs width and height on images rendered through its native Image Blocks and Product Gallery blocks — keep images in these native blocks rather than embedding raw <img> tags in Code Blocks.
2. Avoid using Code Blocks to inject images or external embeds above the fold; use native Squarespace content blocks wherever possible.
3. Fonts: Go to Design > Fonts and choose from Squarespace's built-in font library. These are loaded with font-display: swap by Squarespace's renderer. If you have added custom fonts via Design > Custom CSS (@font-face), add font-display: swap; to each declaration.
4. Announcement bars and banners: Use the native Announcement Bar (Pages > Announcement Bar) rather than injecting a banner via Settings > Advanced > Code Injection. The native bar is pre-sized in the layout.
5. Third-party scripts and pop-ups: Scripts added via Settings > Advanced > Code Injection (Header) run early and can cause CLS. Move non-critical scripts to the Footer injection area. Configure any pop-up or chat widget to be position: fixed so it does not displace page content.
6. Cookie banners: Use Squarespace's built-in Cookie Banner (Settings > Cookies & Visitor Data) which renders in a fixed position. Third-party cookie scripts injected into the header are a common CLS culprit on Squarespace — switch to the native option.

<img
  src="product-photo.jpg"
  alt="Red running shoes"
  width="800"
  height="800"
  style="aspect-ratio: 1/1; width: 100%; height: auto;"
>

/* CSS: reserve space for an ad slot before it loads */
.ad-container {
  min-height: 90px;   /* match your largest ad unit height */
  width: 100%;
}

/* CSS: prevent font-swap layout shift */
@font-face {
  font-family: 'MyFont';
  src: url('/fonts/myfont.woff2') format('woff2');
  font-display: swap;
}

What is cwv cls?

Cumulative Layout Shift (CLS) measures how much the visible content on your page unexpectedly moves while it is loading. Every time an image pops in and pushes a button out of reach, a font swaps and reflowing text, or a banner ad shoves your product description down the page, that counts as a layout shift. Google's "good" threshold is a CLS score below 0.1; a score of 1.05 — as in the example above — means content is shifting dramatically, which is easily noticeable to shoppers. The most common causes are images and videos without explicit width/height attributes, web fonts that change character sizes when they load, third-party widgets (chat bubbles, review carousels, cookie banners, email pop-ups) injected above existing content, and dynamically inserted banners or promotional bars.

CLS is one of Google's three Core Web Vitals, which are a direct ranking signal in Google Search — a poor score can push you below competitors even if your content is better. Beyond rankings, layout shift is a serious conversion killer: a shopper who taps "Add to Cart" while the page is still loading can accidentally hit the wrong element, leading to frustration and cart abandonment. Google's own research links poor page experience scores to higher bounce rates and lower revenue per session. On mobile devices — where Google indexes first — layout shift is even more pronounced because screens are small and a single banner inserting itself at the top can move everything else off screen.

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