Cumulative Layout Shift (CLS) is one of the most frustrating user experience issues on the web.
You’ve seen it before:

These sudden layout jumps are not just annoying — they destroy conversions, hurt credibility, and significantly damage your Core Web Vitals.

Google hates CLS.
Users hate CLS.
And high-performing websites simply cannot afford it.

In this article, we break down exactly what causes layout shifts, how they affect your performance, and the step-by-step process Domizwebs uses to fix CLS issues permanently.

1. What is Cumulative Layout Shift (CLS)?

CLS measures how much visible content unexpectedly moves around the screen while the page is loading.

If something pushes the layout down, up, or sideways while a user is interacting, you get a layout shift.

Google uses CLS as a Core Web Vitals metric to determine how stable and usable a site feels.

CLS Score Guidelines (Google):

2. Why Fixing CLS Matters (More Than Most Businesses Realize)

Fixing CLS is not just about Google scores. It directly affects:

2.1. Conversions

Unexpected layout shifts cause misclicks, frustration, and drop-offs.

A single shift can cost:

2.2. User Trust

If the page jumps around, users subconsciously feel:

Trust drops instantly.

2.3. SEO & Rankings

CLS is part of Core Web Vitals, and poor performance can push your pages lower on Google results.

2.4. Mobile Usability

Since mobile screens are small, even tiny shifts have a massive impact on usability.

3. What Causes CLS? (The Real Reasons Behind Layout Shifts)

Most layout shifts come from unassigned space or late-loading elements.

Here are the most common causes:

3.1. Images Without Dimensions

This is the #1 reason for CLS.

If you don’t define width/height in HTML or CSS, images load “blind,” pushing elements as they appear.

3.2. Ads, Banners & Embeds

External content loads unpredictably and often forces the layout to move.

Examples:

3.3. Fonts Loading Late (FOIT & FOUT)

When fonts load after text is displayed, the size changes — causing a layout jump.

3.4. Lazy-Loading Elements Without Reserved Space

Lazy-loading is great, but if no space is reserved, the layout collapses until the element loads.

3.5. Dynamically Injected Content

Examples:

If they appear suddenly without reserved space, you get CLS.

3.6. Incorrect Flexbox or Grid Behavior

Sometimes CSS layouts reflow unexpectedly because:

3.7. Sliders & Carousels

If not properly sized, sliders cause massive layout shifts on load.

4. How to Fix CLS Issues: The Ultimate Step-By-Step Guide

Below is the exact process Domizwebs uses to eliminate CLS issues permanently.

Step 1: Always Set Width & Height for All Images

Every image MUST have fixed dimensions.

✔ Good Example:

<img src="hero.jpg" width="1400" height="800" alt="Hero Image">

Why it works:

The browser instantly reserves the exact space needed before the image loads — preventing movement.

Also recommended:

Step 2: Reserve Space for Ads, Banners & Embeds

Never allow ads or embeds to load dynamically without space allocated.

Example:

Wrap them in containers with fixed height.

<div style="height: 300px;">
  <!-- Ad loads here -->
</div>

If you can’t predict the exact height, set a reasonable minimum.

Step 3: Preload Important Fonts to Prevent Shifts

Late-loading fonts cause text jumps.

Fix it with:

<link rel="preload" href="/fonts/Poppins.woff2" as="font" type="font/woff2" crossorigin>

And ALWAYS include a fallback font with similar spacing.

Step 4: Avoid Late-Injected Content Above Existing Elements

If popups, banners, or announcement bars appear at the top of the page, they push everything down.

Solutions:

Step 5: Set Fixed Dimensions for Videos & Iframes

Videos often cause massive layout shifts.

Use a responsive wrapper:

<div class="video-container">
  <iframe src="video"></iframe>
</div>

With CSS:

.video-container {
  aspect-ratio: 16/9;
}
.video-container iframe {
  width: 100%;
  height: 100%;
}

Step 6: Fix Sliders, Carousels & Hero Sections

Unstable sliders are a major CLS culprit.

To fix:

✔ Pre-set the exact slider height
✔ Preload the first slide image
✔ Avoid auto-resizing slides
✔ Make the container height responsive and fixed

Step 7: Optimize Lazy-Loading Properly

Lazy-loading images or iframes is good — IF done right.

Use:

<img loading="lazy">

BUT make sure:

Never lazy-load the hero image — it causes huge shifts.

Step 8: Manage Dynamic Elements Carefully

Elements like:

Should NEVER push content.

They must overlay the page instead.

Step 9: Avoid Layout Jumps From CSS

Some CSS changes applied late cause shifts:

Avoid:

Use:

Step 10: Test CLS with the Right Tools

These tools show EXACTLY where shifts occur:

✔ Chrome DevTools → Performance → “Layout Shift Regions”

Shows highlighted areas that jump.

✔ PageSpeed Insights

Reports CLS issues with specific elements.

✔ Lighthouse

Gives live visualizations of shifts.

✔ Web Vitals Chrome Extension

Shows live CLS scoring as you load the page.

5. The Most Common Real-World CLS Problems (And How We Fix Them Fast)

Here are real examples we fix for clients regularly:

Problem 1: Homepage banner jumps when loading

Fix: Preload banner image + set fixed height + avoid lazy-loading.

Problem 2: Text jumps when font loads

Fix: Preload fonts + set fallback font + enable font-display: swap.

Problem 3: Product images cause layout shifts

Fix: Add width/height attributes + use aspect-ratio containers.

Problem 4: Popups push page down

Fix: Use overlays that float instead of pushing content.

Problem 5: Blog pages shift as ads load

Fix: Pre-reserve ad space + load asynchronously.

Problem 6: Mobile layout shifts due to dynamic menu

Fix: Replace push-down menus with overlays.

6. The Domizwebs Advantage: How We Fix CLS Better Than Standard Agencies

Most agencies stop at “add width and height.”

We go further by addressing ALL root causes:

✔ Full-page layout stability audit
✔ Image dimension indexing
✔ Script loading restructuring
✔ CSS refactoring
✔ Font strategy optimization
✔ Dynamic content management
✔ Layout shift monitoring over time
✔ Speed optimization to boost other Core Web Vitals

When we eliminate CLS issues, we do it permanently — not temporarily.

7. Final Thoughts: CLS Is One of the Easiest Core Web Vitals to Fix — If You Know What You’re Doing

Most CLS problems come from:

Fixing them dramatically improves:

If you want a website that ranks high, feels smooth, and never jumps around…

Domizwebs builds sites with perfect layout stability from day one.

👉 Get your website optimized here:
https://domizwebs.com/#contact