Mastering the Art of User-Friendly Websites: Demystifying Cumulative Layout Shift

Introduction: Creating a website is like arranging pieces of a puzzle. Each element, from images to text, contributes to the overall experience. Imagine reading an article, and suddenly the text shifts, causing you to lose your place. That annoying jump is what we call Cumulative Layout Shift (CLS). In this blog, we’ll break down this concept into bite-sized pieces and explore why it matters in the world of web design.

Understanding Cumulative Layout Shift (CLS):

1. What is Cumulative Layout Shift?

Simply put, Cumulative Layout Shift is the unexpected movement of elements on a webpage. It happens when things like images or ads load slower than the rest of the content, pushing everything else around. Think of it as trying to read a book while someone keeps moving the paragraphs. Frustrating, right?

2. How is CLS Measured?

CLS is measured on a scale from 0 to 1. A score of 0 means no shifting, while 1 indicates a significant amount of movement. Google, in its quest for a better web, considers a CLS score below 0.1 as good and anything above 0.25 as poor.

Why Does CLS Matter?

1. User Experience (UX):

Picture this: You’re shopping online, ready to hit the ‘Buy Now’ button, and suddenly the page shifts, making you click on something else accidentally. That’s a classic CLS problem. It’s irritating for users and can lead to a poor shopping or browsing experience.

2. SEO Impact:

Google, the search giant, loves websites that offer a seamless experience. Websites with low CLS scores tend to rank higher in search results. So, if you want your website to be in Google’s good books (and who doesn’t?), minimizing CLS is a smart move.

Tackling Cumulative Layout Shift:

1. Image and Video Optimization:

Optimize your images and videos to ensure they load quickly. Use appropriate sizes and formats, and lazy loading can be a friend here – it delays the loading of less critical elements.

2. Reserve Space for Ads and Embedded Elements:

If your site includes ads or embedded elements, reserve space for them in advance. This way, when they load, they won’t push other content around.

3. Load Critical CSS Early:

Critical CSS contains the styling information needed for the initial view of the page. Loading it early minimizes the chances of unexpected shifts.


In the world of web development, paying attention to Cumulative Layout Shift is like putting together a smooth dance routine – you want everything to flow seamlessly. By understanding what CLS is, why it matters, and how to tackle it, you’re taking a giant step towards creating websites that users not only visit but enjoy navigating. After all, in the dance of the internet, no one likes surprise moves that throw them off balance. So, let’s keep the web dance floor smooth, engaging, and CLS-free!

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