// glossary entry

Critical CSS

Definition: The minimum amount of CSS code needed to display the upper, immediately visible portion of a page, embedded directly in the HTML instead of being loaded from an external file.

Everyday analogy: It’s like when you’re moving and you only pack the most essential box, containing a bed, a blanket, and a coffee maker, into the car so you can get by on the first night. The rest follows later.

How we use it: In the PageSpeed audit, we reduce render-blocking with Critical CSS, usually one of the most effective ways to improve LCP.

// synonyms

  • Above-the-Fold CSS
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