Technical SEO

CLS (Cumulative Layout Shift)

Quick Definition

CLS measures unexpected visual movement during page load. The 'good' threshold is under 0.1.

In context

Common causes: images without width/height attributes, web fonts swapping (FOIT/FOUT), ads loading without reserved space, and dynamically inserted banners above existing content. Fix by reserving space for all dynamic content with explicit dimensions.

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