CLS in SEO: Understanding the importance of visual stability for web pages

Through our SEO Agency Optimize 360

La Cumulative Layout Shift (CLS)is a term of growing importance in the field of natural referencing and website optimisation. This metric aims to evaluate the visual stability of a web page and its impact on theuser experience.

In this article, we'll explain what CLS is in SEO, why it's essential and how to improve your site's performance in terms of visual stability.


What is the Cumulative Layout Shift?

Le Cumulative Layout Shift is an indicator that measures the movement of the visible elements of a web page during loading or use.

It is calculated by multiplying the offset of each element by its relative share in space visible of the page. The closer the index is to zero, the less likely the user is to encounter unwanted movements on the page.

To better understand why this measure is important, imagine yourself reading an article on a site and suddenly an image appears and moves all the content downwards, forcing you to search for the location where you were.

This kind of unpleasant situation can have a negative impact on the user experience and encourage your visitors to leave your site quickly.

CLS, a key metric for SEO

The Google search engine attaches particular importance to user experience and website performance. It is in this context that CLS has become a key indicator to monitor in order to improve a site's natural referencing.

Why is CLS important in SEO?

    • The user experience First and foremost, a low CLS guarantees an overall satisfactory experience for users. They can consult content without being disturbed by intrusive elements or unwanted movements.

    • Site performance The CLS is linked to the loading speed pages and their stability. These factors are also ranking criteria for Google. A good CLS therefore helps to improve your chances of being well positioned in the search results.

    • Engagement signals Studies have shown that a high CLS can generate a bounce rate time spent on the site and a reduction in the number of visits to the conversions. By reducing the time lag, you increase the chances of retaining your visitors and improving these key indicators.

What threshold should you set for your CLS?

According to Google, here are the recommended target values for the Cumulative Layout Shift:

    • Good CLS: A CLS of less than 0.1 is considered ideal for delivering an optimal user experience.
    • To be improved CLS: If your CLS is between 0.1 and 0.25, this indicates that there are shifts on the page but that their impact is moderate. You should aim to reduce these shifts to improve the user experience.
    • Bad CLS: A CLS of more than 0.25 means that the movements are too great and risk seriously damaging your visitors' experience. It is imperative to intervene quickly to correct the problems encountered and thus promote better natural referencing.

How can I reduce the Cumulative Layout Shift on my site?

To improve the stability of your web pages, here are a few recommendations to put into practice:

Explicitly reserve the necessary space for media elements

To prevent images and videos from lagging during loading, it is preferable to specify their size (height and width) in the code HTML or via CSS. This will allow the browser to instantly reserve the necessary space and avoid resizing during loading.

Load ads and other dynamic elements into reserved spaces

If your site includes advertisements, widgets or other dynamic elements, it is important to reserve enough space to display them without disrupting the main content. You can, for example, use containers with fixed dimensions to accommodate these elements while preserving the visual stability of the page.

Avoid late style changes

Shifts can also be caused by style (CSS) modifications applied too late when the page is loaded. Try to avoid nested styles and declare important CSS rules upstream to ensure that they are taken into account from the start of rendering.

Optimising fonts and animations

Loading fonts and running animations can also generate undesirable movements on your pages. To limit these problems, use system fonts or optimised font services, and don't hesitate to deactivate complex animations or animations that take a long time to load.

By working on these different aspects, you will not only improve your site's SLC, but also help to provide a satisfying and enjoyable user experience for your visitors. There's no doubt that this approach will pay dividends in terms of natural referencing and the success of your site. website.

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