Core Web Vitals & WCAG 2.2 AA

01Distinguish a target from a measurement

Kiln’s brief specifies 97% mobile CWV pass, 0.8-second LCP, 0.00 CLS and a 13.8 KB base JavaScript budget. Those are illustrative product targets on this website. They are not measured results for your store or an independently verified competitor comparison. Record the date, URL, device, tool and configuration when publishing a benchmark.

02Measure the store customers actually use

Use PageSpeed Insights or Search Console to inspect available Chrome UX Report field data. Field Core Web Vitals assess the 75th percentile of real experiences over a rolling period. Lab measurements help diagnose problems but do not establish a field pass rate. Low-traffic origins may not have enough CrUX data.

1. Record LCP, INP and CLS for representative templates on mobile and desktop.
2. Separate field data from Lighthouse or local lab tests in every report.
3. Test a fully configured store with real images, apps, consent tools and localisation.
4. Compare the same sample, date range and device category when comparing themes.

03Protect the performance budget

Serve correctly sized images, reserve their dimensions and prioritise the actual LCP image. Defer offscreen media, avoid autoplaying heavy video on mobile and load feature scripts only where used. Review app embeds after each installation.

1. Use responsive image sizes and modern image formats supported by your platform.
2. Limit font families and weights; use font-display to keep text available.
3. Avoid synchronous third-party scripts in the critical rendering path.
4. Measure before and after each new integration rather than relying on bundle size alone.

04Audit the final store for accessibility

WCAG 2.2 AA is a technical conformance target requiring the complete experience to meet all applicable success criteria. Semantic HTML and a compliant-looking theme are not sufficient. Merchant colours, content, apps and checkout can introduce failures.

1. Navigate every menu, filter, drawer and checkout entry point using only the keyboard.
2. Check visible focus, logical focus order and focus return after modals close.
3. Use labelled controls, descriptive links, useful image alternatives and announced status changes.
4. Test text contrast, reflow at zoom, error identification and touch target sizes.
5. Respect reduced motion and avoid conveying meaning by colour alone.
6. Combine automated checks with manual screen-reader and keyboard testing.

05Understand EAA responsibilities

European accessibility obligations depend on the service, jurisdiction, dates, exemptions and the merchant’s circumstances. WCAG conformance supports accessibility work but is not a standalone legal compliance certificate. Use a qualified accessibility professional to assess your complete storefront and obtain jurisdiction-specific advice when required.