It is important to Reduce unused CSS as not doing so can greatly lead to performance-related problems to your website. Also, reducing the unused CSS can minimize the render-blocking behavior that can result in speeding up the page load of your website. As a website owner, you must be aware of the fact that generally the CSS are considered to be render-blocking. This is because they tend to delay the First Paint till the browser has been able to complete executing them. According to the layout and the visitors device, loading of the CSS rules that are not required to render above the fold content can greatly affect the performance of the web page.
The Different Kinds of Unused CSS
Let us take a look at the different kinds of the unused CSS:
- The Non-Critical Type
These are the CSS rules that are not used to render above the fold content but might still be used in the case of the other pages. These are also used for the purpose of styling below the fold content.
- The Dead CSS Rules
These refer to the styles that are not utilized any longer. These might be remamnents of the previous versions of the sites or even a pair of testing for temporary utilization.
How Does an Unused CSS Effects the Performance of the Web Page
One must know that in case of each page loads, the browser works by parsing, downloading and executing the stylesheets before being able to render something on the webpage. This is mainly because, the stylesheets by themselves comprise of certain rules that tend to affect the page styling. These need to be established before the browser is able to display any content.
So, you see, incase if the stylesheets comprise of any non-critical or dead CSS rules then they can lead to being unnecessarily bigger than required. Hence, it is only obvious that larger is the CSS files, much longer is the time taken by the browser to be able to download, execute or even parse. Now, as these files get larger than required, this can lead to the blocking of the browser from being able to tend to the other critical tasks. This results in delaying the First Pint of the page, and also increasing the time taken by the visitors when waiting for the display to appear over the page. Therefore, it is important to reduce the amount of unused CSS as it can minimise the execution time by the browser and also the bandwidth consumption. This way you can enjoy a speedier page load.
Methods to Reduce the Unused CSS
Now that you know what is meant by the CSS and what they can lead to, let us take a look at how to reduce the unused CSS:
- In case of the non-critical CSS Rules
For this, you need to consider the following steps:
Inlining the Critical CSS
As the name suggests, you need to inline the critical CSS directly to the HTML of the webpage.
Code-Splitting CSS
You can separate the non-critical CSS with the help of code-splitting. By doing so, the render blocking behavior can be minimized. This happens as the critical CSS gets loaded first followed by the remaining non-critical CSS.
- For the Dead CSS Rules
In case of the Dead CSS Rules you need to review the CSS code, and then eliminate any CSS rules that are not needed. Also, you need to follow this step when it comes to duplicate or similar rules that contribute into minimizing the CSS footprint.
- In case of the WordPress Users
As minimizing of the unused CSS for your webpage is not an easy task, hence you can use the WordPress plugin to assist you with the task.
How the Unused CSS Affects the Performance of the Website?
As most of you might be knowing that the <link tag is the basic way to add the style to your web page.
Here the main ‘main.css’ file downloaded by the browser is called the external stylesheet. This is because it is stored separately from the HTML that is used by it. This is why s browser needs to download, parse and also process all the stysheets that are external encountered prior to it displaying or rendering a content on to the screen of the user. So, you see, it does not makes any sense for the browser to try and display the content before the stylesheets have been processed. This is because the stylesheets can also comprise of the rules that can affect the process of page styling. Hence, every external stylesheet needs to be downloaded from the network. This can greatly increase the time taken by the user before they are finally able to view the web content.
