Question 1

What is backdrop-filter in CSS?

Accepted Answer

backdrop-filter applies visual effects to the area behind an element. Unlike filter (which affects the element itself), backdrop-filter blurs, adjusts brightness, or applies other effects to content beneath a semi-transparent element. It's the core of the glassmorphism effect.

Question 2

Why is my backdrop-filter not working?

Accepted Answer

The most common reason is the element's background isn't transparent. backdrop-filter only shows when the background lets light through: background: rgba(255,255,255,0.1) or background: transparent. If background is a solid color, the filter effect is obscured. Also include -webkit-backdrop-filter for Safari.

Question 3

Does backdrop-filter affect performance?

Accepted Answer

backdrop-filter can be expensive — the browser must read, filter, and composite the pixels behind the element on every paint. Avoid applying it to large areas or many elements simultaneously. Use will-change: backdrop-filter sparingly to optimize performance before animation.

CSS Backdrop Filter Generator

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