Does CSS block page rendering?

Yes, CSS blocks page rendering. The browser must load and process all CSS files associated with the document before displaying the content to the user. This is because CSS affects the visual styling and layout of elements, and the browser tries to avoid the 'flickering' effect or incorrect display.

Therefore, CSS is considered a render-blocking resource. To optimize loading, you can:

• Minimize and combine CSS files.
• Use media attributes for deferred loading of styles that do not affect initial rendering.
• Load critical CSS inline, and the rest asynchronously.

This helps speed up page rendering and improves user experience.