Remove Unused CSS (Deprecated)
Remove CSS for Better Page Load Performance
How to Remove Unused CSS
There are a few different methods to reduce the amount of CSS on your pages. One of the ways to optimize this process is to ensure as you are creating new pages that the CSS is optimized during the building process. That will end up saving you a lot of time later. Another method is to remove any CSS rules that are obsolete. There are third-party tools that can crawl your pages and determine if the CSS on the page can be optimized further.
Unused CSS: Final Thoughts
And in addition to that, asynchronous loading, which we discussed in an earlier section, can be implemented to load CSS content that is not necessary for anything above-the-fold. You are not necessarily removing it from the page, but to the user, the page is loading fast and not being slowed down by any CSS. Removing CSS can be a frightening task. No one likes to remove anything because it might break something further down the stream, so find a tool, or someone who is extremely knowledgeable with your site to make these changes.
Lighthouse is an open-source tool that is used to run an audit against your web pages and provides scores and suggestions for improving page performance, accessibility, SEO, and more.
PageSpeed Insights is a tool created by Google that reports on the performance of a page on both mobile and desktop devices, and provides suggestions on how that page may be improved.