In today's fast-paced digital world, having a website with an outstanding user experience is crucial for success. One critical aspect of creating a seamless web experience is managing Cumulative Layout Shift (CLS), which plays a significant role in user engagement and overall site performance.
In this guide we'll explore what CLS is, why it matters, and share practical tips to optimize your website's layout stability effectively.
Understanding Cumulative Layout Shift (CLS)
Cumulative Layout Shift (CLS) is a metric that measures the frequency and severity of unexpected layout shifts caused by changes in web page elements during loading, which can negatively impact user experience.
Definition And Importance
Cumulative Layout Shift (CLS) is a crucial metric used to quantify the visual stability of a webpage, focusing on how much elements within the viewport move or shift as the page loads.
When a website has high CLS scores, it signals that there are unexpected layout changes making it difficult for users to interact with and navigate through the site.
The importance of optimizing CLS lies not only in providing a better user experience but also in affecting search engine rankings. In May 2021, Google introduced Core Web Vitals as part of its ranking algorithm, with CLS being one of these vital metrics alongside Largest Contentful Paint (LCP) and First Input Delay (FID).
Websites with poor CLS scores may suffer from decreased visibility on search engines and consequently miss out on valuable organic traffic. Furthermore, an unstable webpage layout can lead to frustrated users abandoning your site or failing to convert which ultimately impacts revenue goals.
Causes Of CLS
Cumulative Layout Shift (CLS) can be caused by a variety of factors, such as images and videos without proper dimensions, ads that take up space before rendering, and third-party scripts that load asynchronously.
Another common cause is lazy loading or defer loading content without reserving the space it will occupy when loaded. Unexpected changes in layout as users interact with the webpage can also contribute to CLS.
These causes often result in a less stable user experience, which negatively impacts engagement and conversion rates.
Impact On User Experience
Cumulative Layout Shift (CLS) can have a significant impact on user experience. When web pages experience sudden and unexpected layout shifts, users may become frustrated and confused, leading to higher bounce rates or lower conversion rates.
For example, if an image loads slowly or is not sized correctly, it could push text down, causing the user to lose their place in the content they were reading.
Furthermore, a high CLS score can negatively affect search engine rankings since Google's Core Web Vitals now include this metric as part of its ranking algorithm. Thus it is essential for SEO specialists to optimize websites for CLS as improved scores lead not just to better UX but also increased revenue generation via better search engine rankings.
Tips For Improving CLS
To improve CLS, optimize images and videos by including width and height attributes, use proper sizing and positioning of elements, implement pre-loading techniques, prioritize above-the-fold content, and minimize the impact of third-party scripts through asynchronous loading.
Optimize Images And Videos
One of the main causes of CLS is images and videos that load slowly or shift unexpectedly on the page. Optimizing these media elements can help improve layout stability and reduce CLS scores.
This involves minimizing file sizes, using appropriate formats (such as JPEG for photos), and including width and height attributes. Dimensionless images should be avoided because they can cause unexpected shifts in layout as they load.
For video content, utilizing a lazy-loading technique where videos only start loading when the user scrolls close enough to it can also help prevent large layout shifts during page load.
Moreover, providing alternative text descriptions helps users with visual impairments better understand the content without affecting site's performance or causing unintended layout shifts.
Use Proper Sizing And Positioning Of Elements
Proper sizing and positioning of elements can greatly improve Cumulative Layout Shift (CLS) on your website. By setting the correct dimensions for images and ads, you can ensure that they don't shift or resize unexpectedly, reducing layout shifts and improving user experience.
For example, if you have a banner ad at the top of your page, make sure it's sized correctly so that it doesn't push down other content when loading. Similarly, if you're using dynamic content such as chatbots or pop-ups, take care to position them in a way that doesn't interfere with other parts of the page layout.
Implement Pre-loading Techniques
Pre-loading techniques involve loading page assets before the user needs them, reducing the chances of layout shifts when the page is in use. This can include preloading fonts or images and using lazy-loading for off-screen elements.
By preloading these resources, you ensure that they are available to load right away when a user interacts with your website.
Preloading can also help improve CLS scores by allowing browsers to reserve space for certain layouts ahead of time, minimizing unexpected shifts that occur after content loads on the page.
Also, proper pre-loading of third-party scripts and ads can reduce their impact on CLS scores.
Prioritize Above-the-fold Content
Prioritizing above-the-fold content is an important factor for improving Cumulative Layout Shift (CLS) and enhancing the user experience. Above-the-fold content refers to the visible part of a webpage that appears before scrolling down.
It typically includes headlines, images, and call-to-actions that can capture users' attention and encourage them to explore more of the website.
To prioritize above-the-fold content, make sure they load first by optimizing their size and weight or using lazy loading techniques if needed. You can also consider reducing the number of ads or dynamic elements in this area to minimize any potential disruptions caused by their loading times.
Minimize The Impact Of Third-party Scripts
Third-party scripts can significantly contribute to high CLS scores, as they often load asynchronously and cause unexpected layout shifts. To minimize their impact, it's important to evaluate whether or not a script is necessary for the website's functionality.
If it is deemed necessary, consider using asynchronous loading so that it doesn't block other page elements from loading. By optimizing the script's size and reducing its dependencies, this can help reduce its load time and minimize its impact on CLS.
Measuring And Monitoring CLS
To effectively measure and monitor CLS, utilize tools such as Google's PageSpeed Insights, Lighthouse, or Web Vitals to set performance goals and regularly track progress toward optimizing the user experience on your website.
Tools For Measuring CLS
Measuring and monitoring CLS is essential to improving the user experience on your website. Fortunately, there are several tools available that can help you do just that.
Google's PageSpeed Insights, Lighthouse, and Web Vitals all provide metrics for measuring CLS along with other critical performance indicators such as loading speed and layout stability.
These tools allow you to set performance goals and track your progress over time by providing detailed reports assessing your site's performance based on various parameters like mobile optimization, browser compatibility, code optimization, image dimensions, space management, and more.
Setting Performance Goals
Measuring and monitoring your website's cumulative layout shift (CLS) is essential for understanding how it impacts user experience. Setting performance goals to reduce CLS should be a top priority, with the aim of achieving a score of 0.1 or lower.
This involves using tools such as Google PageSpeed Insights, Lighthouse, and Web Vitals to identify areas where improvements can be made. By regularly tracking your site's CLS, you can determine if changes are having an impact on reducing layout shifts and improving user engagement.
A good approach is to set specific targets for decreasing CLS based on historical data and industry benchmarks. For example, aim to reduce CLS by 25% within the next quarter by implementing design elements that prioritize above-the-fold content or optimizing images and videos with proper sizing and positioning techniques.
Regular Monitoring And Optimization
Regular monitoring and optimization of Cumulative Layout Shift (CLS) is essential for ensuring a great user experience. By using tools such as Google PageSpeed Insights, Lighthouse, and Web Vitals, you can easily measure your website's CLS score and gain insights into how to improve it.
Collaboration between designers and developers is crucial in addressing CLS issues effectively. Performance budgeting can also help identify areas where improvements are necessary without sacrificing functionality or design consistency.
Best Practices For Managing CLS
Collaboration between designers and developers, performance budgeting, utilization of Google PageSpeed Insights, Lighthouse and Web Vitals, and avoiding common CLS mistakes are some of the best practices for managing CLS.
Collaboration Between Designers And Developers
Collaboration between designers and developers is crucial for managing Cumulative Layout Shift (CLS). Designers should work closely with developers to ensure that website layouts are stable and consistent.
Developers can then use this information to code the website properly for optimal performance. Collaboration also allows designers and developers to address any layout shift issues early on in the development process.
Effective collaboration leads to better user experience, improved search engine rankings, and increased revenue. It ensures that websites load quickly and consistently across all devices while maintaining design consistency.
Performance Budgeting
As part of the best practices for managing CLS, performance budgeting is an essential technique that can help to ensure optimum website functionality. Essentially, this involves setting a maximum limit on the number and size of resources that are loaded by your website in order to reduce its impact on load times.
By focusing only on key performance indicators (KPIs) such as CLS scores or page speed metrics, you'll be able to prioritize which areas of your site require optimization first, rather than attempting to tackle every possible optimization issue all at once.
For example, suppose you're working on a new WordPress theme with heavy image usage, but you've noticed that these images are causing significant layout shifts when they load dynamically.
Setting a performance budget could enable you to optimize these images before release until they meet target sizes so that they don't cause additional space requirements upon loading.
Utilize Google PageSpeed Insights, Lighthouse, And Web Vitals
It's important to measure and monitor your website's CLS score regularly, and Google PageSpeed Insights, Lighthouse, and Web Vitals are essential tools for doing so.
For example, Google PageSpeed Insights can help you identify issues causing slow loading times or high CLS scores on your web pages. Lighthouse analyzes a webpage’s performance with an eye toward improving it across a variety of factors including accessibility (a key part of SEO) enhancing the viewer experience in ways that improve engagement.
By using these powerful optimization tools along with best practices like preloading assets, prioritizing above-the-fold content, optimizing images and videos for size & placement while keeping them dimensionless will significantly reduce the negative impact from shift layouts on users visiting to your website.
Avoiding Common CLS Mistakes
In order to improve Cumulative Layout Shift (CLS) and provide a better user experience, it is essential to avoid common CLS mistakes. One of the most common mistakes is not using dimensions for images and videos on your website.
By providing width and height attributes for images, you can prevent layout shifts from occurring when the page loads.
Third-party scripts can also be a major contributor to high CLS scores if they are loaded synchronously or without preloading techniques. To reduce their impact, use asynchronous loading or defer them until after other elements have loaded.
What's more, failing to optimize code and reducing unnecessary DOM elements can lead to slower load times and increased CLS scores.
Conclusion
Improving Cumulative Layout Shift (CLS) is a crucial step towards enhancing website user experience. By understanding the causes of CLS and implementing strategies to reduce it, websites can achieve better search engine rankings, increased engagement with users, and higher conversion rates.
The tips outlined in this guide provide useful insights into how designers and developers can optimize images, prioritize above-the-fold content, minimize third-party scripts' impact, measure CLS scores and monitor its optimization regularly.
Remember that a good CLS score is 0.1 or lower; therefore, optimizing your site's layout stability should be an integral part of any SEO strategy aimed at providing the best user experience for visitors.
