What is CLS by device
CLS by device shows Cumulative Layout Shift (CLS) values across different device types (e.g., Mobile or Desktop). This lens helps you identify which devices are experiencing more layout instability and negatively affecting the visual experience.
The list includes only devices that generated traffic to your website during the selected period.
Common reasons for poor CLS on certain devices include rendering delays, font swaps, image loading behavior, or layout differences between mobile and desktop — all of which may cause unexpected shifts.
Healthy CLS by device sample
A healthy CLS by device lens shows all green — meaning your layout is stable across the major device types your users are browsing with.
Some variation between devices is normal, but if none of them hit yellow or red, your visual stability is under control.
Unhealthy CLS by device sample
In the example below, Mobile is the most unstable device type. This may lead to higher bounce rates, increased exits, and reduced trust — especially if layout shifts interrupt key actions like clicks, navigation, or reading.
Common causes include:
Elements shifting after fonts load.
Dynamic containers that appear after the page begins rendering.
Missing dimensions on media or banners that push other elements around.
Resolving unhealthy CLS by device
Go-to action plan to resolve an unhealthy CLS by device:
Ask Uxi to analyze your CLS by device values and suggest improvements
Use Filters to focus on the unstable device type and correlate with other CLS lenses (e.g., CLS by page, country, or third party).
Simulate CLS of the suspected lens to see if fixing it will resolve the CLS by device. If yes, this is where the resolution focus should be.
Use an automated CLS optimization tool like Navigation AI to improve your CLS by device values
Once you’ve improved CLS, set an alert to be the first to know if it starts worsening again.
Try it yourself
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