3 Ways To Remove Unused CSS To Improve The PageSpeed Performance

To improve a website’s PageSpeed performance, Google PageSpeed Insights or Lighthouse always recommends “remove unused CSS” (currently you can see as reduce unused CSS). Like most website owners, are you also facing the same recommendation again and again?

CSS (cascading style sheets) is one of the core resources used to make a website stylish. However, sometimes, using unused CSS rules can harm the website’s PageSpeed performance.

Here, we will explain what unused CSS is and the reason behind it. Also, we will cover why we need to remove the unused CSS and finally explore the effective 3 ways to remove unused CSS from your website.

What is unused CSS?

Unused CSS indicates CSS codes that are not applied or utilized in any element of the current website design but still exist in the CSS stylesheets. This unused CSS unnecessarily increases the web page’s size, which can negatively affect the website’s page loading time. Let’s understand this with an example.

Assume, on your website, there was a form on the homepage. However, after updating the website’s design you add a checklist instead of the form and also add some CSS styles for the checklist.

The styles applied in the form of the homepage can still exist in the CSS stylesheets, increasing the CSS file size and slowing down the website’s PageSpeed performance.

Note: If you want to optimize your CSS file effortlessly, you can use RabbitLoader to get a non-coding and more efficient solution.

The most common facts that cause unused CSS

Before diving into the solution, first, it’s essential to know the reason behind the presence of unused CSS in a website. Let’s discuss the most common facts for an unused CSS:

1. Applying too many generic styles

Applying too many generic styles, which do not specify any particular element, can increase the probability of unused CSS in the CSS stylesheet.

Hence, it is always recommended to not use too many generic styles if you are also concerned about the website’s PageSpeed performance.

2. Using external libraries and framework

During the web development process, most developers often use external libraries and frameworks to make the process easier. However, most frameworks or libraries consist of many pre-defined CSS classes and rules.

Thus, using a bundle of libraries or frameworks without removing the unused CSS rules can typically increase the size of the CSS file, which can slow down the website’s PageSpeed performance.

3. Frequently update the website’s design

If you are changing the website’s design frequency, sometimes, developers may forget to remove the CSS rules. This can lead to an unused CSS. Hence, when you are changing the website design frequently, you must delete the CSS rules that are not needed for the current web design.

Why do you need to remove unused CSS?

Here, we will discuss the importance of removing the unused CSS from the CSS stylesheets.

1. Reduce the total page file size

While unused CSS can typically increase the page size, removing it can reduce the total page file size. The page loading time depends on the page size. Hence, reducing page size significantly can improve a website's page loading time.

2. Improve the user experience

As a website owner, your first priority should be providing a seamless user experience. Removing the unused CSS can speed up the website’s page loading time, which can enhance the user experience.

No matter how much time you invest in on-page and off-page SEO, ignoring the PageSpeed performance can ruin your all efforts. In simple words, let’s say you invest a fair amount of time in website design, but if it takes a long time to load, most of the users will leave the website before seeing the design. So, removing unused CSS is essential to provide a better user experience.

3. Boost the core web vitals performance

Google PSI always determines a website’s PageSpeed performance based on the Core Web Vitals metrics. Removing unused CSS improves the LCP and INP performance, which can lead to a better PageSpeed performance score in Google PSI.

The 3 ways to remove unused CSS

Let’s see the 3 effective ways to remove the unused CSS from a website.

1. Manually removing the unused CSS

To manually remove unused CSS, you need to first identify the unused CSS code from the CSS stylesheet. For this, you can use the Google Chrome DevTool. After identifying the unused CSS rules, you can remove them manually.

2. Using an Automation tool

Manually removing the unused CSS can be daunting if you don’t have any expertise in web development. It can also be risky, as one small mistake can destroy the website design.

The best way is to optimize your CSS files using an automation tool like RabbitLoader, WP Rocket, or others. In the case of RabbitLoader, when you install it, along with the other resource files, it will also optimize your CSS file by reducing unused CSS and generating critical CSS.

3. Customize CSS framework

You already know that the external CSS framework can also have some CSS rules that are not needed in website design. The best practice is to use a framework’s built-in customization tool, such as Bootstrap, which allows you to select the CSS rules needed for web design.

Conclusion

We hope that after reading this article, you can understand unused CSS and the importance of removing it. Here, we have also mentioned 3 ways to remove unused CSS. Thus, if you are also struggling with poor PageSpeed performance due to unused CSS, you need to remove it for better PageSpeed performance.