Getting rid of Cumulative Layout Shift (CLS) is essential for providing a stable and user-friendly web experience. CLS measures how much content visually shifts on a webpage during loading or interaction, which can be disorienting and frustrating for users. Here are some tips to help you reduce and eliminate CLS:

  1. Set Dimensions for Images and Media:
    • Always specify width and height attributes for images and video elements in your HTML. This prevents the content from changing size when the media loads.
  2. Use CSS for Aspect Ratios:
    • Instead of relying on the default dimensions of images or video elements, use CSS to set aspect ratios. This ensures that the space for media is reserved, even before it loads.

css

/* Example for maintaining a 16:9 aspect ratio */ .video-container { position: relative; padding-bottom: 56.25%; /* 9/16 */ overflow: hidden; } .video { position: absolute; width: 100%; height: 100%; }

  1. Preload Fonts and Web Fonts:
    • Use the preload attribute to load fonts and web fonts early in the rendering process. This reduces the chance of a FOIT (Flash of Invisible Text) or FOUT (Flash of Unstyled Text) causing layout shifts when fonts load.

html

<link rel="preload" href="your-font.woff2" as="font" type="font/woff2" crossorigin="anonymous">

  1. Defer JavaScript Execution:
    • Defer non-essential JavaScript execution, especially scripts that might manipulate the DOM and cause layout changes. Use the async or defer attributes for script tags.
  2. Avoid Dynamically Injected Content:
    • Be cautious when adding content dynamically to the page. If you must do so, ensure that you reserve the space for the content before it loads to avoid layout shifts.
  3. Optimize Ads and Embeds:
    • If your page displays ads or third-party embeds, make sure they are properly sized and don’t cause layout shifts when they load. Utilize ad placeholders to reserve space.
  4. Monitor CLS with Performance Tools:
    • Use browser developer tools and performance monitoring tools like Lighthouse, PageSpeed Insights, or Web Vitals to monitor and identify CLS issues on your website.
  5. Test on Various Devices and Browsers:
    • Ensure that your site is responsive and doesn’t exhibit layout shift issues on different devices and browsers.
  6. Regularly Review and Optimize:
    • Periodically audit your website for new layout shift issues, especially when making updates or adding new content.
  7. Provide Feedback to Users:
    • If layout shifts are inevitable due to dynamic content loading, consider providing visual cues or placeholders to indicate to users that content is loading and may cause a shift.
  8. Avoid Using Absolute Positioning for Important Elements:
    • Elements positioned using position: absolute can cause layout shifts if they overlap with other content. Use this CSS property sparingly, especially for critical page elements.
  9. Reserve Space for Loading Elements:
    • When you expect dynamic content (e.g., comments, chat widgets) to load, reserve space for it beforehand to prevent sudden layout shifts when it appears.
  10. Optimize Responsive Design:
    • Ensure that your responsive design adapts gracefully to various screen sizes and orientations, minimizing the risk of content shifts on different devices.
  11. Preload Images with Correct Dimensions:
    • When preloading images using the preload attribute, make sure the dimensions in your preloaded image match the actual image’s dimensions. This avoids CLS caused by changes in image size.
  12. Implement a Content Management System (CMS) Wisely:
    • If you’re using a CMS to manage your website, configure it to generate stable HTML output. Some CMS platforms may introduce unnecessary layout shifts due to their default behaviors.
  13. Use the transform Property for Animations:
    • When animating elements on your page, consider using CSS transforms (translate, scale, rotate, etc.) instead of properties that affect layout (top, left, width, height). Transforms typically don’t trigger layout changes and are less likely to cause shifts.
  14. Test with Real User Data and Network Conditions:
    • Test your website’s performance, including layout stability, with real user data and various network conditions to simulate real-world scenarios. This can help you identify and address CLS issues that might not be apparent in controlled testing environments.

By following these tips and maintaining a proactive approach to layout stability, you can minimize and ultimately eliminate Cumulative Layout Shift on your website, creating a more pleasant and user-friendly experience.