How to Optimize CSS to Improve Website Loading Speed
By Catherrine Garcia ; May 21st, 2018

As a web developer, your job is not only to create feature-rich web applications and websites, but also make them load fast. The digital world demands perfection, and that's why you cannot ignore website loading speed optimization.


In this article, we will focus on one aspect of website loading optimization, i.e., optimize CSS to make the website load fast.


CSS is one of the crucial parts of a website. After all, it gives the HTML skeleton the look and design. Clearly, there are many ways you can optimize CSS. But, before we start, let's understand the importance of having a faster website.

Why we need a faster website?

1.    Visitors have less patience. Generally, if a website takes more than 2 seconds, it will start losing visitors.

2.    Faster websites also perform better in Google search engine.

3.    User's experience is improved significantly with a faster website.

4.    Conversion rates skyrocket thanks to a faster website.


If you are still not convinced, let's take a look at numbers. If your website loads more than 3 seconds, 40% of the visitors will leave. Not only that, almost half of the visitors expect the site to load under 2 seconds. What's next? Even 79% of shoppers don't like a slow eCommerce website, and they are likely to share their experience with their friends. In short, it is important to make your website as fast as possible. If you are starting as a blogger, you also need to understand that speed is as important as the content you post.

Tips to Optimize CSS to Improve Website Loading Speed

CSS is not a programming language. It is style sheet language, or we can say it is a markup language. So, how do you optimize it? Let's get started.

1. Remove unnecessary code

CSS code can be written in many ways. This means you can perform the same desired result by writing it differently. Also, many developers write CSS code twice for an element. This can lead to a cluster. The best way to solve it to use a tool that detects unnecessary code. We recommend using It is free and extremely beneficial at the same time.

2. Image Sprites

Images play an important role on a webpage. For developers, it is just impossible to ignore images. However, they can be optimized, thanks to image sprites. Image sprites is a simple technique by which images are mashed up into one file, eventually reducing your CSS file size. In return, your page load time also decreases considerably.

3. Minify CSS

Minification is a process of CSS code. It is a very effective technique used in web development. By using this technique, you can compress CSS code. It deletes all the unnecessary white space. You can find tons of CSS minification tool online. We recommend using CSSMinifier.


Let's take a look at an example.


#lione {
  font-size: 2em;
  color: steelblue;

#first {
  font-size: 1em;
  color: red;

#linext {
  font-size: 2em;
  color: black;

#next {
  font-size: 1em;
  color: orange;

#lithird {
  font-size: 2em;
  color: blue;

#third {
  font-size: 1em;
  color: pink;

#lilast {
  font-size: 2em;
  color: brown;

#one {
  font-size: 1em;
  color: green;


That's an unminified CSS code. Let's minify it with the tool that we have provided.




Look's unreadable, right? But, it does its work. Also, the code can also be minified using the other tools. So, there is nothing to worry.

4. Optimize CSS Performance

Whenever a page loads, HTTP requests go to the server. So, if your website makes a CSS request, it will send another HTTP request. This means that there will be multiple CSS requests to the server, slowing the website considerably. The solution is to combine all the separate CSS files into one file and then server it to the user. This will make the website download at once and will stop the browser sending multiple requests to the server.


Even though, it has been fixed with the new and improved HTTP/2, combining CSS into one file can improve your website loading time.


5. Load CSS and JavaScript after everything else loads

One of the best ways to improve site speed

 is to put both CSS and JavaScript at the bottom of your HTML page. This will make both of them load at the last moment when a user requests a website. By then, the website will load above the fold ensuring fast loading time. The user will be able to see the page load fast, and not leave it. Technically, the page is still loading, but that will not interfere with the user experience until and unless the visitor scrolls down fast.

6. Keep it Simple Stupid

The last point that we want to discuss is KISS. KISS technique dictates that you should always try for simplicity rather than complexity. The end goal is to write CSS that is easy to read, non-repetitive, error-free, and is well organized. All of these points will ensure that your CSS code is optimized from the start. Also, if you feel, rewriting the CSS code, you can always do it as it will surely optimize it.

What else you can do?

Improving your website loading require optimization at various level. This means that you need to do a lot more than just optimizing your CSS code. You also need to optimize the other code in your website. Also, you can CDN to improve loading time further. Caching is also a great option and should be enabled from the start.


Speed optimization is an ongoing process. It starts from the time you start developing your website. Even when you upload an image to your website, you need to make sure that the image is optimized correctly. One poorly optimized image can make your site slow by a significant margin.


So, what did you learn from the article? Comment below and let us know.

About author

Catherrine Garcia is currently working at as a web developer. She is also a passionate blogger and loves to share her knowledge through articles on various technical topics.

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