What is CLS
The Cumulative Layout Shift (CLS) is a user-centric metric that measures the visual stability of a web page. It measures how often users experience unexpected layout changes. A low CLS indicates that the page is stable and that its use offers a quality user experience. Here are some pointers on what CLS is and how to consider it in your SEO strategy.
UX matters
The acquisition of a good CLS score does not depend on chance, everything is done according to Google‘s standards. It considers that a page offers a good experience to its users when its CLS score is below 0.1. To be sure to reach this score on desktops and mobile devices, it is necessary to take into account the 75th percentile of page loading time.
User-initiated Layout Shifts
A layout shift is only bad if the user does not expect it. Layout Shifts that occur in response to user interactions (clicking on a link, pressing a button, typing in a search box and the like) are acceptable and accepted as long as the shift occurs as a result of an interaction and the effect is obvious to the user. If an interaction triggers a network request that takes some time, it is better to immediately create space on the page to display a loading indicator, in order to avoid an unpleasant layout change at the end of the request.
Good practices
Size your images and videos. Allocate a defined space before they are loaded. As with videos and images, reserve space for your ad blocks to prevent them from moving other elements when they are displayed. Avoid dynamically added content with Javascript. Avoid animations that change the size of your element (height and width): use transform: scale () instead. Don’t move your elements by modifying the top, right, bottom, or left properties.
Google Search Console
Google Search Console allows you to do a Core Web Vitals audit to measure the CLS of a web page. By doing a quick analysis, you will get information about slow pages, fast pages and pages to improve. It also provides information about the CLS of pages. It shows which pages have abnormal CLS, and most importantly, it groups them together automatically.
Remember: SEO specialists must perform CLS diagnostics, identifying problems and implementing recommended solutions to achieve good CLS scores for their sites.