Google PageSpeed Insights often suggests “reduce unused CSS (previously known as remove unused CSS)” to speed up a WordPress website. This ”remove unused CSS” is one of the most common Google PSI recommendations that most of WordPress site owners often can see during the PageSpeed analysis.  

Removing unused CSS manually may require extensive knowledge of CSS coding. However, with the help of a WordPress plugin, you can remove unused CSS without any coding knowledge. 

Here, we will discuss unused CSS rules, the importance of removing them, and how to remove unused CSS manually. Finally, we will mention some WordPress plugins that allow you to do it without any effort. 

What Is Unused CSS?

CSS files are one of the core resources in a WordPress website as they add style and make your WordPress website more attractive. 

However, some CSS rules can exist in the CSS stylesheet that are not utilized in the current web design. These rules are known as unused CSS or dead CSS. Several reasons can be there behind unused CSS such as code updates, design changes, or others.  

Having too much unused CSS can negatively impact the PageSpeed performance of a Wordpress website. Let’s understand this in a simple way. 

During the page rendering, the browser generally parses the HTML file. When the browser comes across a CSS file, it starts to load and execute the CSS file. As unused CSS rules can increase the size of a CSS file, it takes more time to load them, slowing down the WordPress website. 

Understanding The Importance Of Removing Unused CSS

As you can see, having too many unused CSS rules can slow down a website’s PageSpeed performance. In this section, we will mainly concentrate on the importance of removing unused CSS from the CSS stylesheets. 

• Improving The Page Loading Time

While, having too many unused CSS rules is responsible for typically increasing the CSS file size, by removing the unused CSS rules from the CSS file, you can significantly reduce the CSS file size, reducing the total page file size. 

The page loading time depends on the total page file size along with other factors like network speed. Hence, reducing the total page file size can significantly improve the page loading time. 

• Enhance The User Experience 

No matter how well-designed the website is or how much effort you put into its on-page and off-page SEO, waiting a long time to load your website’s content may increase the user’s frustration, which leads to a high bounce rate. 

As you know, a poor user experience can directly affect your WordPress site’s conversion rate (the percentage of users who convert to potential leads). Hence, removing unused CSS can enhance the user experience, which in turn leads to a better conversion rate. 

• Pass The Core Web Vitals Assessment And Get A Good PageSpeed Score

During analyzing the PageSpeed performance in Google PageSpeed Insights, the first thing you can see is the Core Web Vitals assessment. Google developed a set of performance metrics to determine a website's initial page loading time, responsiveness, and visual stability, and based on them, it can provide a performance score. 

Removing unused CSS can improve page loading time, which improves Core Web Vital's performance. It also increases the chance of achieving a good PageSpeed score in Google PSI. 

How To Remove Unused CSS Manually?

First, you need to identify the CSS rules that are not utilized in the current design and then manually remove the unused CSS rules. Several tools, like Google Chrome DevTool, can identify unused CSS. Let’s see how to check them in Google Chrome DevTool. 

After right-clicking on the web page and clicking on Inspect, you can see the Chrome DevTool. Then press “cntrl+shift+p” and select “show coverage” and reload the page. The solid red color indicates the percentage of unused CSS. After clicking on Sources, you can see the unused CSS. 

Once you can identify the unused CSS rules, you can easily remove them from the CSS stylesheets. However, manually removing the CSS rules involves risks, as accidentally removing a critical CSS can destroy the entire web design. 

The Helpful Plugins To Remove Unused CSS 

Removing unused CSS is one of the advanced web optimization features. Hence, only a few plugins can help you remove unused CSS. Let’s see the most helpful tools that you can use to remove unused CSS without having any coding knowledge. 

RabbitLoader

RabbitLoader become one of the popular WordPress plugins due to its all-in-one features. When you are installing RabbitLoader, along with the other resource file’s optimization, it will also optimize your CSS file by removing unused CSS and generating critical CSS.  

By identifying the critical CSS rules, RabbitLoader will create a separate file and serve them to the users as a high fetch priority. This significantly improves a WordPress website's initial page loading time.   

Asset CleanUp

On the other hand side, you can also use the Asset CleanUp plugin which mainly focuses on HTML, CSS, and JavaScript optimization. 

After detecting all the page’s assets, this plugin makes a list of all unused CSS rules and JavaScript functions in the dashboard. After examining them, you can delete them and speed up your WordPress website.   

Conclusion 

Removing unused CSS is essential in order to achieve a better PageSpeed performance. Here, we have discussed, what unused CSS is and the importance of removing them. If you have knowledge of CSS and are ready to take risks, you can try this manually. Otherwise, the best way is to use any WordPress plugin to remove the unused CSS.