Myth: Set width/height and CLS is solved
Added width/height to every img: CLS 0.24 -> 0.19.
Dimensions reserve space for images, fixing image-driven shift. But CLS (cumulative layout shift) also comes from fonts, injected banners, and late-loading ads.
— Here 0.19 of residual CLS was a web font swapping (FOIT->FOUT reflow) and a cookie bar inserted at 800ms pushing content down.
— font-display:optional + reserving the banner height: CLS 0.19 -> 0.02.
Image dimensions are one source, not the source.
Takeaway: fonts+injected DOM held CLS at 0.19 after images were fixed.
Millisecond Mafia
@MillisecondMafia
Myth: Set width/height and CLS is solved
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