Fix Guide

How to Eliminate Render-Blocking CSS

Stop large stylesheets from delaying first paint by inlining critical CSS and deferring the rest.

Medium High Impact 30 min

Why It Matters

The browser will not paint anything until it has downloaded and parsed the CSS in the <head>. A big blocking stylesheet pushes back your LCP. Inlining the small slice needed for above-the-fold content and loading the rest asynchronously fixes this.

How to Fix

Extract critical CSS

Generate the minimal CSS needed to style above-the-fold content and inline it in the <head>.

Load the rest async

Load the full stylesheet with a non-blocking pattern so it doesn't hold up the first paint.

Trim unused CSS

Run DevTools Coverage to find and remove unused rules — frameworks often ship far more CSS than a page uses.

Code Fix

html

Before (broken)

<link rel="stylesheet" href="/styles.css">  <!-- blocks first paint -->

After (fixed)

<style>/* critical above-the-fold CSS inlined here */</style>
<link rel="stylesheet" href="/styles.css" media="print" onload="this.media='all'">

Platform-Specific Instructions

WordPress

WP Rocket and LiteSpeed Cache both have "Optimize CSS Delivery" / critical-CSS options that automate this.

Next.js

Next.js inlines critical CSS for the route automatically; keep global CSS small and prefer CSS Modules / Tailwind.

Check with our tool

CSS Minifier

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How to Eliminate Render-Blocking CSS — Fix Guide | SlapMyWeb