Operations
CLS (Cumulative Layout Shift)
CLS measures unexpected layout movement during page load — content jumping as images load, ads appear, fonts swap. Target: under 0.1. High CLS = bad UX + ranking penalty.
More detail
Fixes for poor CLS: (1) declare width + height on all images so the browser reserves space, (2) reserve space for ads + embeds, (3) use font-display: optional or swap with size-adjust to prevent FOUC, (4) avoid inserting content above existing content after page load. Aiprosol's design system uses fixed aspect-ratios on all images.