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Introduction
CSS files play a central role in the visual rendering of a website. However, their size or accumulation can adversely affect loading performance.
Fasterize's CSS application allows you to optimize your style sheets by reducing their size and limiting their number, in order to load pages faster and improve the user experience.
Why is it important to optimize your CSS files?
CSS files are often loaded as a priority in the <head> pages. Unlike other files, they block rendering until they are fully charged.
⚠️ The larger or more numerous your CSS files are, the longer your pages will take to load.
Optimizing CSS is therefore essential, regardless of:
- the type of device or browser,
- the quality of the network connection,
- or the user's geographic area.
👉 Learn more about the impact of CSS on web performance
What Fasterize does for you
Fasterize acts on two optimization axes:
- the size of CSS files through minification,
- the number of CSS files through bundling.
CSS minification
Minification removes unnecessary spaces, comments, and characters from CSS files. It is enabled by default on Fasterize.
💡 You can exclude specific files from this minification by defining them as targets.
CSS bundling
The CSS Bundle option allows you to merge multiple CSS files into a single file.
- Limited to 4 files per package
- The generated file retains the original URLs as comments.
- Fewer HTTP requests = faster loading
Move On Top: prioritize CSS
The option Move On Top move the tags <link> styles at the top of the HTML page, which allows:
- faster and more stable content display,
- a reduction in the effects of layout shift (CLS).
💡 CLS (Cumulative Layout Shift) is a key indicator of visual stability. The lower it is, the better the user experience.
Web performance advantage
🚀 By optimizing CSS files, you improve:
- First Contentful Paint (FCP),
- Largest Contentful Paint (LCP),
- the Speed Index,
- and you reduce the CLS.