How To Minify CSS To Improve The PageSpeed Performance by 10%

Google PageSpeed Insights suggests you need to minify CSS to improve a website’s PageSpeed performance. As a website owner or technical SEO expert, when you come across the “minify CSS” suggestion during performance auditing Google PSI, you think it may require extensive CSS knowledge (it’s also true unless you use RabbitLoader) and avoid it, which may slow down the website.

CSS is a website’s core resource. It makes a website stylish. However, sometimes, an unoptimized CSS can harm the website’s PageSpeed performance by increasing the total page file size.

 Hence, to reduce the CSS file size, you need to minify the CSS file along with other CSS optimization strategies such as generating critical CSS and reducing the unused CSS styles from the CSS stylesheets. 

Here, we will explain CSS minification and its importance. To clear your doubts, we will also explain the difference between CSS minification and compression.

Finally, we will explore how RabbitLoader helps you to minify the CSS file without any expertise in coding & we will mention the three alternative tools to minify CSS and improve the PageSpeed performance.

Understanding Minify CSS

Developers often use comments, line breaks, and white space to make the CSS file easily readable and understandable. However, these characters are not needed during the web page rendering time, and they unnecessarily increase the CSS file size as well as the total page file size.

CSS minification is a technical process of removing these unnecessary characters from the CSS file size without affecting functionality and reducing the file size. Let’s understand CSS minification with an example. 

Before minifying the CSS file, it looks like:

/* add a paragraph styling */

p {

font-family: arial;

color: red;

background-color: grey;

}

/* add the links color to green */

a:links {

color: green;

}

a:visited {

color: blue;

}

As you can see, two comments, some line breaks and white spaces are added to the CSS file, which unnecessarily increases its size. By minifying the CSS file, you can remove these unnecessary characters from the CSS code. 

Let’s see how a minified CSS looks like:

P{font-family:arial;color:red;background-color:grey;}a:link{color:green;}a:visited{color:blue;}

It’s noticeable that the above minified CSS code is smaller than the original CSS file. Hence, minifying CSS can improve the website’s PageSpeed performance by reducing the CSS file size

Why You Need to Minify CSS 

After understanding how to minify CSS, the question may arise: Is it necessary to improve page speed performance? 

The answer is yes! Minifying CSS is one of the essential PageSpeed optimization techniques that has several benefits which include:

• Reduce the total page file size
• Reduce the page rendering time
• Pass the core web vital assessment and achieve a good Google PSI score

Reduce The Total Page File Size

In web development, the total page file size indicates the total size of page resources such as HTML files, CSS stylesheets, Javascript and media files. According to Google, for better PageSpeed performance, the total page file size needs to be within 1600 KB. If the page size exceeds 1600 KB, an “avoid enormous network payloads“ warning is encountered in Google PSI tests. 

Minification of the CSS file along with the other resource files can significantly reduce the total page file size and improve the page loading time.

Reduce the Average Page Rendering Time

Page rendering time measures the time between a user’s visit to a website and the page’s content being displayed on the user’s browser. This page rendering time has a huge influence on the user’s first impression of your website. 

CSS minification is one of the crucial steps of CSS optimization. It can typically reduce the average page rendering time and enhance the user experience, which can lead to achieving a desirable conversation rate.

Pass the Core Web Vital Assessment and Achieve a Good Google PSI Score

Core web vitals are a set of performance metrics based on which Google can determine a website’s PageSpeed performance and provide an overall score in Google PageSpeed Insights. 

Minifying CSS files can significantly improve the core web vitals metrics, especially the Largest Contentful Paint (LCP) and the Interaction to Next Paint (INP). Hence, by minifying the CSS file, you can pass the core web vitals assessment and achieve a good Google PageSpeed Insights (PSI) score. 

Let’s see the threshold values for LCP time.

In the case of INP time:

The Difference Between CSS Minification and Compression

While the purpose of CSS minification and compression is almost the same: reducing the CSS file size without affecting its functionality, there are a few differences between their functionality. 

Many new web developers and technical SEO experts are often confused between CSS minification and compression. They can’t differentiate between these two web optimization processes. Here, we will clear all the confusion. Let’s explore the difference between CSS minification and compression. 

As mentioned earlier, CSS minification is a process of deleting unnecessary characters such as comments, line breaks, and white spaces from the coding file and reducing the CSS file size.

On the other hand, CSS compression is a technical process for reducing code redundancy in a CSS file. Implementing a compression algorithm like GZIP or Brotli can significantly reduce the CSS file size by replacing the repeated strings with a single pointer.  

Note: RabbitLoader compresses your HTML, CSS and JavaScript files by using the advanced brotli algorithm and reduces the file size significantly to speed up the website’s PageSpeed performance.

Minify CSS file with RabbitLoader

Minifying CSS manually takes a lot of time. Especially when you have a large website, this process can be daunting. Here you can take the help of an optimization tool like RabbitLoader in order to make the process easier.  

After installing RabbitLoader plugin on your website or adding RabbitLoader for other platforms for the website’s Page speed optimization purpose, RabbitLoader will automatically remove all the unnecessary characters from the CSS file. Not only CSS files, but RabbitLoader also minifies HTML and JavaScript files. 

Apart from minifying the CSS file, RabbitLoader also optimizes CSS by generating the critical CSS (most optimization tools are unable in the WordPress ecosystem to create critical CSS) and removing the unused CSS (the CSS style that is not needed in the current website design). 

By optimizing the CSS file, RabbitLoader significantly reduces the CSS file size as well as the average rendering time.

As you can see in the above image, the CSS file size was 2.3 MB before optimizing the website mymandap.in, exceeding Google’s threshold value.  However, after installing the RabbitLoader, the overall CSS performance improvement is 98%. The CSS file size is reduced to just 39.4 KB. Therefore, the average rendering time was also reduced to 287.9 ms from 10959.1 ms. 

If you want to know more about how RabbitLoader improves the PageSpeed performance, read our case study “thestudio.com”.

The Alternative Helpful Tools to Minify CSS

We already discussed how Rabbitloader helps you minify CSS files. This RabbitLoader is available for WordPress sites, WooCommerce, Shopify, Laravel and PHP-based websites. Here, we will mention some alternative tools if you need to minify CSS code for a single page or file.

1. UnCSS

UnCSS is an online CSS minifier tool that removes unnecessary characters like comments and line breaks from the CSS file and reduces the CSS file size. Here, you just need to paste the CSS code and click on the “UNCSS MY STYLES” button. 

2. Prepostseo

You also can use Prepostseo minifying the CSS file. In order to minify the CSS file in prepostseo, you need to paste the CSS code or upload the CSS file and click on the “Minify CSS” button. Not only CSS, this online tool also allows you to minify an HTML and JavaScript file. 

3. SEOMagnifier 

SEOMagnifier is an online CSS minification tool like Prepostseo where we just need to click on the “Submit” button after pasting the CSS code. Also, you can upload the CSS file. Along with the CSS minification, it also compresses the CSS file. 

Conclusion  

Here, we have already covered every way to Minify CSS. We have also discussed the difference between CSS minification and compression to clear up confusion. Let’s quickly recap the importance of minifying the CSS file which includes: 

• Reduce the total page file size
• Reduce the average page rendering time
• Improve the Core Web Vitals assessment. 

Finally, we have explored how RabbitLoader improves your website’s PageSpeed performance by minifying the CSS file along with the other web optimization processes. 

If you are struggling with a slow page loading speed on your website and trying to optimize its PageSpeed performance, install RabbitLoader and improve your website’s PageSpeed performance.