<b>Reserved Min-Height Containers vs Empty Ad Divs</b>

<b>Reserved Min-Height Containers vs Empty Ad Divs</b>

The single cheapest CLS fix nobody bothers with: wrap every ad slot in a div with a fixed min-height matching the largest size in your sizemap.

What it does — holds layout space before the ad loads, so nothing jumps when it fills.
Setup effort (1/5) — one CSS rule per slot, or a templated mixin.
RPM lift seen — indirect but real: sites moving CLS from 0.25 to under 0.1 saw +6 to +11% RPM as Core Web Vitals lifted organic sessions.

Pros — near-zero effort, helps SEO and AdSense quality signals at once.
Cons — reserves space even for unfilled slots, so a white gap appears on no-fill. Use a collapse-on-nofill fallback.

Lift: ★★★☆☆ — Risk: ★☆☆☆☆
Best for: anyone with multi-size slots. Nobody should skip this one.