Critical CSS - Inline Above-the-Fold Styles

Learn how to extract and inline critical CSS to eliminate render-blocking stylesheets and improve First Contentful Paint (FCP).

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What is Critical CSS?

Critical CSS is the minimum CSS required to render above-the-fold content. By inlining it directly in the HTML, you eliminate render-blocking stylesheet requests.

How to Implement Critical CSS

1

Generate Critical CSS

Use tools like Critical, Penthouse, or CriticalCSS to automatically extract above-the-fold styles.

2

Inline in HTML Head

Add extracted CSS in a <style> tag in the document head.

3

Load Full CSS Asynchronously

Use media='print' with onload to load the full stylesheet without blocking render.

Frequently Asked Questions

Keep inlined critical CSS under 14KB (one TCP round trip). Larger amounts can actually hurt performance.

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